Some adjectives are invariable (they don't agree in gender and number with the noun they refer to).
Among these:
1. The adjective pari / even, equal (and the adjectives that are derived from it, such as dispari / odd; impari / uneven, unbalanced):
Examples:
- Due è un numero pari / two is an even number
- È una lotta impari / It's an unbalanced struggle
- Pari opportunità / Equal opportunities
2. Some adjectives describing colours:
- blu / blue
- rosa / pink
- viola / purple
Examples:
- Il tuo cappotto è blu / Your coat is blue
- I miei guanti sono blu / My gloves are blue
- Anna non trova più la sua sciarpa blu / Anna can't find her blue scarf
3. Compound adjectives referring to shades of colours, such as bianco-grigio / white-grey
azzurro carta da zucchero / powder blue and so on (you obtain them by joining together two adjectives describing colours):
Examples:
- Il suo cappotto è grigio-azzurro / His coat is grey-blue
- L'ala grigio-azzurro della sera / The grey-blue wing of the evening
- Hai visto la mia tazza da tè azzurro carta da zucchero? / Have you seen my powder blue mug?
4. Adjectives formed by the prefix anti + noun:
Examples:
- I fari antinebbia / The fog lights
- Il liquido antigelo / The antifreeze
5. The infinitive form of the verb avvenire (to happen) used as an attribute:
Examples:
- I giorni avvenire / The days ahead
- Le generazioni avvenire / Future generations
(Rarely written separately a venire - which literally means "to come" —> giorni a venire / days to come)
6. Some adverbial forms used as adjectives, such as perbene (decent, respectable) and dappoco (worthless):
Examples:
- È un uomo perbene / He's a decent man
- Sono gente perbene / They're decent people
- Sei un uomo dappoco / You're a worthless man
- Siete persone dappoco / You're worthless people
