Suffix · forms adjectives
Turns a noun into an adjective meaning "full of" or "having that quality": danger becomes dangerous.
Written by Bryan López, English teacher · Updated
The suffix -ous (or -ious) takes a noun and creates an adjective meaning "full of" or "having that quality". From "danger" you get "dangerous"; from "fame" you get "famous"; from "glory" you get "glorious". The meaning is always "having or producing [the noun]". A dangerous place is one that has danger. A famous person is one who has fame. Once you know the noun, the adjective is one step away.
This is a big win for Spanish speakers: -ous/-ious almost always corresponds to -oso/-ioso in Spanish. dangerous = peligroso famous = famoso glorious = glorioso nervous = nervioso serious = serio/grave Note the spelling difference: English has no accent and uses -ous (not -oso). But the pattern is the same and the words are instantly recognisable.
When the base noun ends in silent -e, it is usually dropped before -ous: fame → famous, nerve → nervous. When it ends in -y, that -y becomes -i: glory → glorious, victory → victorious. The variant -ious appears when the root needs that extra vowel sound to flow naturally: ambition → ambitious, religion → religious.
Base rule: noun + ous. Two frequent spelling changes apply.
When the root ends in a soft vowel or in patterns like -tion, -ious is used instead of -ous: ambition → ambitious, religion → religious, space → spacious. When in doubt, say the word aloud — your ear will guide you.
-ous / -ious/əs/ · soft, unstressed 'us'
Tap the button to hear how the ending sounds. Each word in the table has its own audio.
danger ends in a consonant, so just add -ous: danger + ous = dangerous. No extra -e-.
When the noun ends in -y, that -y becomes -i before -ous: glory → glorious, victory → victorious.
The silent -e in "fame" is dropped before -ous: fame → famous.
A trick to remember it
Think of -ous as the English -oso/-ioso: dangerous = peligroso, famous = famoso, glorious = glorioso. If Spanish uses -oso, English almost always uses -ous. And remember: a final -y becomes -i (glory → glorious).
Exercise 1 · Form the word
Exercise 2 · Pick the right one
What is the correct adjective form of "glory"?
Exercise 3 · Pick the right one
"famous" comes from...
The suffix -ous / -ious turns a noun into an adjective meaning "full of" or "having that quality": danger becomes dangerous. In Spanish it usually maps to -oso / -ioso.
The ending -ous / -ious is pronounced /əs/ · soft, unstressed 'us'. For example, "dangerous".
"danger" becomes "dangerous". It is a typical example of the -ous / -ious suffix.
-tion, -ness, -ful, -ly, -able... every ending you need to understand thousands of words at once.