Suffix · forms nouns
Turns an adjective into the noun that names that abstract quality: active becomes activity.
Written by Bryan López, English teacher · Updated
The suffix -ity takes an adjective and turns it into the abstract noun that names that quality. From "active" you get "activity"; from "able" you get "ability"; from "real" you get "reality". It is the -ness equivalent for Latin-origin adjectives. The practical difference: if the adjective ends in -ive, -al, -ous or -ic, its noun almost always uses -ity (not -ness).
This is probably the suffix with the most direct cognates between English and Spanish: activity = actividad reality = realidad quality = calidad community = comunidad university = universidad Almost every Spanish -idad word has an English -ity equivalent, and vice versa. It is a vast source of free vocabulary in both directions.
When you add -ity, the stress moves to the syllable immediately BEFORE -ity. This can change how the root sounds. active [ˈæktɪv] → activity [ækˈtɪvɪti] (stress jumps to -tiv-) possible → possibility (stress jumps to -bil-) This does not affect meaning, but it does affect pronunciation. Practise with the words in the table to internalise the stress shift.
Adjective (usually Latin-origin) + ity. One frequent spelling change applies.
Adjectives ending in -ive drop the -e and add -ity: active → activity. Adjectives ending in -ous drop -ous and add -osity: curious → curiosity. For -le adjectives (possible, able), -le becomes -ility: possible → possibility, able → ability.
-ity/ɪti/ · stress falls on the syllable just before -ity
Tap the button to hear how the ending sounds. Each word in the table has its own audio.
In English it is -ity, not -idad. actividad = activity, realidad = reality.
possible → possibility. The -le becomes -ility: possibi-lity.
-ive adjectives form their noun with -ity, not -ness: creative → creativity.
A trick to remember it
Every Spanish -idad word almost certainly has an -ity twin in English: curiosidad = curiosity, realidad = reality, posibilidad = possibility. That is a huge bank of free vocabulary waiting to be used.
Exercise 1 · Form the word
Exercise 2 · Pick the right one
What is the noun form of "curious"?
Exercise 3 · Pick the right one
"reality" comes from...
The suffix -ity turns an adjective into the noun that names that abstract quality: active becomes activity. In Spanish it usually maps to -idad.
The ending -ity is pronounced /ɪti/ · stress falls on the syllable just before -ity. For example, "activity".
"active" becomes "activity". It is a typical example of the -ity suffix.
-tion, -ness, -ful, -ly, -able... every ending you need to understand thousands of words at once.