1. not suitable or appropriate for a particular purpose or situation
2. not having a natural ability or tendency to do something

Examples

• His casual remarks were unapt for such a formal occasion.
• The old building proved unapt for modern office use.
• She seemed unapt to follow directions carefully.
• The timing of the announcement was particularly unapt.
• He was unapt to change his mind once decided.
• The metaphor was unapt and confused the audience.