Inappropriate means not suitable for the occasion. Inappropriate dress, an inappropriate remark, wholly inappropriate.
It is a careful word that avoids saying what was actually wrong, which is why it does so much work in official language — inappropriate behaviour can mean anything from a bad joke to a sacking offence, and the vagueness is often deliberate.
1adjectiveinappropriateNot suitable for the occasion.
“Jeans and trainers are inappropriate for a job interview at a bank.”
inappropriate is a quality of unsuitability.
From in- + appropriate.
Etymology from Wiktionary, CC BY-SA