Similar to the spelling changes documented above with nouns, Italian adjectives will often insert an –h in the plural form of adjectives ending in –co, -ca, -go, -ga. E.g.,
bianco > bianchi (white)
stanco > stanchi (tired)
However, this rule does not apply to all masculine nouns ending in –co and –go; you do not insert the “-h-“ in the plural form of such adjectives if the adjective in question places its emphasis on the third-from-last syllable, e.g.,
simpatico > simpatici (nice/kind)
pratico > pratici (practical)
If the adjective in question places its emphasis on the next-to-last syllable (which is standard pronunciation for Italian), then you do insert the “-h-“ E.g.,
antico > antichi (antique/old)
largo > larghi (wide)
Feminine adjectives are consistent in their insertion of the –h for the plural form of adjectives ending in –ca and –ga, e.g.,
bianca > bianche (white)
simpatica > simpatiche (nice/kind)
pratica > pratiche (practical)
lunga > lunghe (long)
Adjectives ending in –ista
Similar to the note above regarding nouns, some Italian adjectives (usually of Greek origin) will end in –ista. This type of adjective only has one form in the singular, but two forms in the plural. E.g.,
una ragazza pessimista
a pessimistic girl
un ragazzo pessimista
a pessimistic boy
due ragazzi pessimisti
two pessimistic boys
due ragazze pessimiste
two pessimistic girls
Observe the following chart with the adjective egoista (selfish):
Invariable adjectives
There are a few adjectives of color that never change their form. For example, the following adjectives never change form:
viola (purple)
rosa (pink)
blu (blue)
For example,
due occhi blu = two blue eyes
tre t-shirt viola = three pink t-shirts