adjective

1. in a state of stupor; dazed; stunned; stupefied
2. lacking normal intelligence or understanding; slow-witted; dull
3. showing or resulting from a lack of normal intelligence; foolish; irrational a stupid idea
4. dull and boring; tiresome [a stupid party]: also used informally as a generalized term of disapproval a stupid hat

Etymology: L stupidus < stupere, to be stunned or amazed < IE *steup-, to strike: see steep

noun