CDS English · Vocabulary
Word forms: one root, four parts of speech
One root gives a noun, a verb, an adverb and an adjective. Read the ending of each word to place it, and solve the leftover by elimination.
Why this matters
Recent papers set match lists where List I names parts of speech and List II gives four forms of one word, and pair items where each option labels two look-alike words. The endings decide most of them in seconds. The few hard ones use a word with no telling ending, such as fast or just, and are solved by elimination.
Concept 1 of 4: Suffixes give away the part of speech
A word's job in a sentence is its part of speech. A noun names a thing or idea, a verb names an action, an adjective describes a noun, and an adverb describes a verb or an adjective. English marks these jobs with endings, so the ending usually tells you the part of speech before you think about meaning.
Definition
Endings to read:
- Noun: -tion, -sion, -ance, -ence, -ment, -ness, -ity, -ledge (supposition, forbiddance, knowledge).
- Verb: the bare base word, or -ate, -ify, -ise, -en (suppose, err, cogitate, intuit).
- Adverb: usually -ly (supposedly, erroneously, knowingly).
- Adjective: -ous, -ive, -ful, -al, -able, and -ed, -en or -ing forms used to describe a noun (erroneous, intuitive, forbidden, supposed).
The method for a match list:
- Find the -ly word first: that is the adverb.
- Find the noun ending next, then the bare verb.
- The word left over is the adjective. Check that it can sit before a noun.
Families tested this way (noun / verb / adverb / adjective):
- 2025 (I): supposition / suppose / supposedly / supposed; forbiddance / forbid / forbiddingly / forbidden.
- 2025 (II): error / err / erroneously / erroneous; knowledge / know / knowingly / knowing; cogitation / cogitate / pensively / cogitative; intuition / intuit / intuitively / intuitive.
Worked example
Match List I with List II. List I: A. Noun B. Verb C. Adverb D. Adjective. List II: 1. Destroy 2. Destructively 3. Destruction 4. Destructive
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
CDS · 2025 · CDS (I) 2025 — English · Q104Easy
Example 1 · Vocabulary · Word Forms and Parts of Speech
Directions: Match List I (parts of speech) with List II (example) and select the answer using the code given below the Lists:
| List I | List II |
|---|---|
| A. Noun | 1. Suppose |
| B. Verb | 2. Supposed |
| C. Adverb | 3. Supposition |
| D. Adjective | 4. Supposedly |
Not every -ly word is an adverb
Friendly, lovely, lonely and costly are adjectives (a friendly dog). In a match list the -ly word is almost always the adverb, but in a sentence check what the word describes.
The -ed form is the adjective, not the verb
In 'suppose / supposed', the verb slot takes the bare form suppose. Supposed and forbidden are past participles used to describe a noun (the supposed winner, forbidden fruit), so they fill the adjective slot.
A word from another root can still fit
In the cogitate set, the adverb was pensively, from a different root. Do not strike it for that. The list asks for the part of speech, not for the family.
Concept 2 of 4: Participle, gerund, infinitive and interjection
Sometimes List I asks for a verb form instead of an adverb. A verb has forms that do other jobs: an -ing form can act as a noun or describe a noun, and 'to' plus the verb makes the infinitive. An interjection is a word that stands alone and shows a feeling or calls for attention.
Definition
The four labels:
- Present participle: the -ing form used as part of a verb or to describe a noun (the intending candidate; she is writing).
- Gerund: the -ing form used as a noun (Neglecting your health is foolish).
- Infinitive: 'to' + the base verb (to experiment, to win). It is two words.
- Interjection: a word that stands alone with a feeling or a call (Hark! Alas! Oh!).
The method:
- Place the noun (-tion, -ment, -ness) and the adjective (-al, -ory, -ent) by their endings.
- The bare word is the verb. The -ing word or the 'to' form takes the special slot.
- An -ing word can also be a plain noun (hearing, building). If the special slot is taken by another word, the -ing word is the noun.
Families tested this way:
- 2025 (I): intention / intend / intending (present participle) / intentional; experimentation / experiment / to experiment (infinitive) / experimental.
- 2025 (I): discrimination / discriminate / discriminating (gerund) / discriminatory; neglectfulness / neglect / neglecting (gerund) / negligent.
- 2025 (II): hearing (noun) / hear (verb) / hark (interjection) / auditory (adjective).
Worked example
Match List I with List II. List I: A. Noun B. Verb C. Gerund D. Adjective. List II: 1. Hesitant 2. Hesitate 3. Hesitating 4. Hesitation
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
CDS · 2025 · CDS (I) 2025 — English · Q102Easy
Example 2 · Vocabulary · Word Forms and Parts of Speech
Directions: Match List I (parts of speech) with List II (example) and select the answer using the code given below the Lists:
| List I | List II |
|---|---|
| A. Noun | 1. Experimental |
| B. Verb | 2. Experiment |
| C. Infinite form of verb | 3. Experimentation |
| D. Adjective | 4. To experiment |
Gerund and participle look the same
Both end in -ing. Ask what the word does. If it is a thing (subject or object), it is a gerund. If it describes a noun or is part of 'is ...-ing', it is a present participle.
An -ing word can be the plain noun
In the hear family, the noun was hearing, because the interjection slot went to hark and the adjective to auditory. Do not force every -ing word into the participle slot.
The infinitive needs 'to'
A single word cannot be the infinitive. If List II has a 'to ...' form, it takes the infinitive slot, and the bare word is the verb.
Concept 3 of 4: Flat adverbs and the odd word out: solve by elimination
Some adverbs have no -ly. 'Run fast', 'work hard', 'go straight': here fast, hard and straight are adverbs with the same form as the adjective. These are flat adverbs. When a set has no -ly word, or has a word from a different root, fix the slots you are sure of and give the leftover word the slot that is left. That is solving by elimination.
Definition
The method:
- Fix the sure slots first: the noun (-ness, -tion, -ice) and the verb (-en, -ify, -ate).
- A superlative (-est) form describes a noun, so it takes the adjective slot (the straightest road).
- A flat adverb (fast, hard, straight, just) takes the adverb slot.
- A word from another root can still be the answer for its slot. Label it by its job, not by its family.
- When two slots are left, try each word in a short sentence.
Sets tested this way (noun / verb / adverb / adjective):
- 2025 (I): justice / justify / just / juridical; straightness / straighten / straight / straightest; hardness / harden / hard / hardy; fastness / fasten / fast / fastest.
- 2025 (II): qualification / qualify / conditionally / qualifying; care / think / carefully / careful; duplication / duplicate / dually / duple.
- 2025 (II): exodus / exit / outward / emanant; spectator / spectate / extremely / spectatorial.
Worked example
Match List I with List II. List I: A. Noun B. Verb C. Adverb D. Adjective. List II: 1. Deepest 2. Depth 3. Deep 4. Deepen
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
CDS · 2025 · CDS (I) 2025 — English · Q110Moderate
Example 3 · Vocabulary · Word Forms and Parts of Speech
Directions: Match List I (parts of speech) with List II (example) and select the answer using the code given below the Lists:
| List I | List II |
|---|---|
| A. Noun | 1. Fastest |
| B. Verb | 2. Fasten |
| C. Adverb | 3. Fastness |
| D. Adjective | 4. Fast |
Hardly is not the adverb of hard
'He works hard' means with effort. 'He hardly works' means he almost does not work. In the hard family the adverb is hard, and hardy (tough, able to survive) is the adjective.
Do not leave the -est word for last
Straightest looks like a degree of straight, so students hesitate. A superlative sits before a noun (the straightest line), so it fills the adjective slot. Then straight is the flat adverb.
Do not strike a word because its root is different
In the qualify set the adverb was conditionally; in the spectator set it was extremely. They break the family but fit the slot. Elimination works only if you place every word.
Concept 4 of 4: Confusable pairs labelled by part of speech
Here two look-alike words are given, and each option labels both words with a part of speech and a meaning. Every option sounds plausible until you check both halves. The wrong options use labels that cannot fit a content word, or keep the labels and swap the meanings.
Definition
The method:
- Strike options that call a content word a determiner (this, that, his), a pronoun, a conjunction or an interjection. Words like compare or illicit cannot be these.
- Check that each meaning sits with the right word. A swapped meaning makes the whole option wrong.
- Then check the part-of-speech label of each word.
- Two words in a pair can share a part of speech. A transitive verb is a verb that takes an object (ensure safety); a phrase is a group of words without its own subject and verb (any way).
Pairs tested this way:
- 2025 (I): elicit (verb, draw out a reaction) / illicit (adjective, forbidden by law); ensure (make certain) / insure (make certain by taking precaution), both transitive verbs.
- 2025 (I): imitate (verb, follow as a model) / intimate (adjective, closely acquainted); compare (verb, estimate or measure) / compere (noun, person who introduces performers); precept (noun, rule of behaviour) / percept (noun, object of perception).
- 2025 (II): lose (verb, misplace) / loose (adjective, slack); anyway (adverb, regardless) / any way (phrase, any manner); allusion (noun, implied reference) / illusion (noun, false idea).
- 2025 (II): appraise (verb, examine and judge) / apprise (verb, inform); climactic (adjective, of a climax) / climatic (adjective, of climate).
Worked example
Prophecy and Prophesy. (a) Prophecy is a verb meaning to predict. Prophesy is a noun meaning a prediction. (b) Prophecy is a noun meaning a prediction. Prophesy is a verb meaning to predict. (c) Prophecy is a determiner meaning a prediction. Prophesy is a conjunction meaning to predict. (d) Prophecy is an adverb meaning a prediction. Prophesy is a verb meaning to predict.
Practice this conceptself-check · 4 quick reps
The same idea in a real exam question:
CDS · 2025 · CDS (I) 2025 — English · Q94Moderate
Example 4 · Vocabulary · Word Forms and Parts of Speech
Directions: In the following items, a pair of words is provided. You are required to select the option that most appropriately describes the meaning of both the words and mark your response on the Answer Sheet accordingly.
Compare and Compere
Right labels, swapped meanings
In the lose / loose item, one option keeps 'verb' and 'adjective' in place but gives lose the meaning 'slack'. Check the meaning of each word, not just the labels. Lose = misplace; loose = slack.
Two words can share a part of speech
Ensure and insure are both transitive verbs; allusion and illusion are both nouns. Do not reject an option just because it gives both words the same label.
One word or two
Anyway (one word) is an adverb meaning regardless. Any way (two words) is a phrase meaning any manner or method: 'Is there any way to help?'. The space changes the meaning.
Summary — formulas & gotchas at a glance
A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.
Watch out for (12)
- Not every -ly word is an adverb→ Suffixes give away the part of speech
- The -ed form is the adjective, not the verb→ Suffixes give away the part of speech
- A word from another root can still fit→ Suffixes give away the part of speech
- Gerund and participle look the same→ Participle, gerund, infinitive and interjection
- An -ing word can be the plain noun→ Participle, gerund, infinitive and interjection
- The infinitive needs 'to'→ Participle, gerund, infinitive and interjection
- Hardly is not the adverb of hard→ Flat adverbs and the odd word out: solve by elimination
- Do not leave the -est word for last→ Flat adverbs and the odd word out: solve by elimination
- Do not strike a word because its root is different→ Flat adverbs and the odd word out: solve by elimination
- Right labels, swapped meanings→ Confusable pairs labelled by part of speech
- Two words can share a part of speech→ Confusable pairs labelled by part of speech
- One word or two→ Confusable pairs labelled by part of speech
Test yourself on Vocabulary
20 past CDS questions from this chapter, timed at 20 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.