stupid
n.n. lacking good sense or intelligence. You use this to describe someone who makes bad choices or something that is not very smart.
n. lacking intelligence, common sense, or the ability to reason effectively. Often used as a pejorative or to describe actions that are ill-advised.
That was a stupid mistake to make.
I felt so stupid when I realized I had been wearing my shirt inside out all morning.
The policy was criticized for being fundamentally stupid, as it failed to account for the most basic logistical challenges faced by the local community.
From Middle French stupide, from Latin stupidus (“struck senseless, amazed”), from stupeō (“be amazed or confounded, be struck senseless”), from Proto-Indo-European (s)tup-, (s)tewp- (“to push, stick”), from Proto-Indo-European *(s)tew- (“to push, hit”). Cognate with Old High German stubarōn (“to be astonished, be stunned, be blocked”). Related also to Old English stoppian (“to block, stop”). More at stop.
Typically used as an attributive or predicative adjective; in informal contexts, it can also function as an intensifier meaning 'very'.