Y06W07VC Word Roots — -ous / -ious (full of)

The suffixes -ous and -ious come from Latin and mean 'full of' or 'having the quality of'. They are added to nouns to form adjectives that describe something possessing a particular quality in abundance. Recognising these suffixes helps students understand the relationship between nouns and their corresponding adjectives across many academic and everyday contexts. This module explores six key words ending in -ous or -ious alongside three further Word Families examples.

Word Families

These three words all contain -ous / -ious. As you read, notice how the meaning 'full of' helps you work out each word.

dangerous

/ˈdeɪndʒərəs/

dan‑ger‑ous

adjective

Likely to cause harm, injury or risk.

Word Breakdown: -ous (suffix meaning 'full of')

Example: Working near unstable floodwaters can be extremely dangerous without proper safety equipment.

Synonyms: hazardous, risky, unsafe

Collocations: a dangerous situation, dangerous conditions, it is dangerous to

curious

/ˈkjʊəriəs/

cu‑ri‑ous

adjective

Eager to know or learn about something; also unusual or strange.

Example: A curious student is more likely to ask questions and explore ideas beyond the set task.

Synonyms: inquisitive, eager to learn, interested

Collocations: curious about, naturally curious, a curious mind

furious

/ˈfjʊəriəs/

fu‑ri‑ous

adjective

Extremely angry or very intense.

Example: The editorial described the community's furious reaction to the delayed emergency response.

Synonyms: enraged, livid, extremely angry

Collocations: furious about, furious at, a furious debate

Academic Vocab

evidence

/ˈevɪdəns/

ev‑i‑dence

noun

Facts, examples or information that support a claim, argument or conclusion.

Word family: evidence (n.), evident (adj.), evidently (adv.)

Example: She cited three pieces of evidence from the text to support her interpretation.

Synonyms: proof, support, data

Collocations: provide evidence, evidence suggests, a piece of evidence

support

/səˈpɔːt/

sup‑port

noun / verb | [support – supported – supported]

To give reasons, evidence or help to strengthen a position or idea. As a noun, the backing or evidence that strengthens something.

Word family: support (n./v.), supportive (adj.)

Example: Every claim in a persuasive text should be supported by at least one piece of relevant evidence.

Synonyms: back up, reinforce, uphold

Collocations: support a claim, support an argument, provide support

justify

/ˈdʒʌstɪfaɪ/

jus‑ti‑fy

verb | [justify – justified – justified]

To show or explain why a decision, opinion or action is reasonable and appropriate.

Word Breakdown: -ify (suffix meaning 'to make or cause')

Word family: justify (v.), justification (n.), justified (adj.)

Example: Students were asked to justify their word choices and explain why each word best suited the context.

Synonyms: explain, defend, validate

Collocations: justify a decision, justify your reasoning, well-justified

demonstrate

/ˈdemənstreɪt/

dem‑on‑strate

verb | [demonstrate – demonstrated – demonstrated]

To show or prove something clearly through evidence, actions or examples.

Word family: demonstrate (v.), demonstration (n.), demonstrable (adj.)

Example: The student demonstrated a strong understanding of the text by using specific quotes in her response.

Synonyms: show, prove, illustrate

Collocations: demonstrate understanding, demonstrate a skill, this demonstrates

prove

/pruːv/

prove

verb | [prove – proved – proved / proven]

To show that something is true or correct using facts or evidence.

Word family: prove (v.), proof (n.), proven (adj.)

Example: The researchers used extensive data to prove that the intervention had a positive effect.

Synonyms: show, demonstrate, establish

Collocations: prove a point, prove that, hard to prove

this suggests

/ðɪs səˈdʒests/

this sug‑gests

phrase

‘This suggests’ is used to explain what a piece of evidence may show or mean.

Example: The character refuses to give up. This suggests that she is determined.

Synonyms: this indicates, this implies, this points to

Collocations: this suggests that; this suggests a link; this suggests the writer

Confusing Words

fewer vs less

Fewer and less are often confused because both mean a smaller amount, but they are used in different situations. Fewer is used with things you can count individually — for example, 'There were fewer students in the library than usual.'

  • fewer — Fewer' is used with things you can count one by one — for example, 'Fewer students were absent this week.'
  • less — Less is used with things you cannot count individually — for example, 'She had less time to complete the task than she had expected.'

Memory rule: A simple rule: if you can count the items one by one, use fewer. If the noun describes an uncountable quantity — such as water, time, energy or information — use less. Ask yourself: can I count them? If yes, use fewer.