Endings: -cious and -tious
Year group: 5/6
Source: DfE, English Appendix 1: Spelling, National Curriculum for England (2013) — Years 5–6, Suffixes
Curriculum requirement: Statutory
Purpose: Years 5–6 guide to adjective endings -cious and -tious — choosing the right form, statutory examples, and practice activities.
The rule
The endings -cious and -tious both make the /ʃəs/ sound ("shus"). They create adjectives meaning "having a great deal of" something, or "full of" a quality.
-cious is used when:
- The related noun ends in -ce → space → spacious
- The base is rooted in Latin -cia or similar
- In most cases where the /ʃəs/ comes after a vowel
-tious is used when:
- The related noun ends in -tion → ambition → ambitious
- The word has a t in its root
When in doubt: look for the related noun. If it ends in -tion, the adjective ends in -tious. If it ends in -ce, use -cious.
Etymology note
Both endings come from Latin. -cious derives from Latin -ciosus; -tious from -tiosus. They entered English via French. The /ʃ/ sound in both is not in the Latin — it developed through French pronunciation and was stabilised in English spelling while the sound shifted. This is why the spelling and sound do not match: the spelling records the Latin root; the pronunciation records the French pronunciation shift.
-cious words
| Word | Related word | Meaning |
|---|---|---|
| vicious | vice | deliberately cruel |
| precious | price/value | of great value |
| conscious | conscience | aware; awake |
| unconscious | un- + conscious | not awake; unaware |
| suspicious | suspicion | distrustful |
| spacious | space | having lots of space |
| delicious | delight/delight | very pleasant to eat |
| ferocious | ferocity | fierce; violent |
| atrocious | atrocity | horrifyingly bad |
| gracious | grace | polite; kind |
| audacious | audacity | bold; daring |
| voracious | voracity | eating greedily; very eager |
-tious words
| Word | Related noun | Meaning |
|---|---|---|
| ambitious | ambition | eager to succeed |
| cautious | caution | careful; wary |
| fictitious | fiction | not real; made up |
| infectious | infection | able to spread disease |
| nutritious | nutrition | providing nourishment |
| superstitious | superstition | believing in luck/magic |
| contentious | contention | likely to cause argument |
| pretentious | pretention | attempting to seem important |
| ostentatious | ostentation | showy; designed to impress |
Tricky cases
conscious / conscience / conscientious
- conscious (-cious): aware, awake
- conscience (noun): the moral sense of right and wrong
- conscientious (-tious, from Latin conscientia): careful and thorough — this is -tious despite seeming like it should be -cious. The t comes from the Latin root conscientiōsus.
suspicious: although suspicion ends in -ion not -tion, the related form is -cious not -tious. The c comes from the Latin suspiciosus.
Common mistakes
| Wrong | Right | Reason |
|---|---|---|
| ambitous | ambitious | ambition → -tious |
| cautous | cautious | caution → -tious |
| delicous | delicious | delic- + -ious → -cious |
| consciencious | conscientious | conscienti- + -ous → -tious |
| spacous | spacious | spac- + -ious → -cious |
Word sort
Find the related noun. Then sort by ending.
Words: ambitious · vicious · cautious · precious · fictitious · conscious · nutritious · spacious · suspicious · ferocious · infectious · delicious
| -cious | -tious |
|---|---|
Dictation sentences
- The ferocious storm made it cautious to venture outside.
- She was ambitious and conscious of every opportunity.
- The delicious and nutritious meal was served in a spacious dining hall.
- His suspicious behaviour during the fictitious game made everyone nervous.
- With precious little time left, she made a conscientious effort to finish.
Source: DfE English Appendix 1: Spelling (2013). All statutory word examples verified against the published statutory word lists for Years 5–6.