Unsuitable means not right for the purpose or occasion. Unsuitable footwear, unsuitable for children, deemed unsuitable.
It judges the fit rather than the thing — nothing is unsuitable in itself, which is why the word always implies a purpose. It is the standard word in film and television age ratings. Note suitable, and suit, from the Old French for following.
1adjectiveunsuitableNot right for the purpose or occasion.
“High heels are unsuitable for a long walk in the hills.”
unsuitable is a quality of poor fit.
From un- + suitable.
Etymology from Wiktionary, CC BY-SA