the.com/dimwit

A brain running on airplane mode while insisting the wifi is fine.

means An insulting term for a person regarded as stupid or slow-witted.

from A straightforward compound from the early 1900s: 'dim,' meaning faint or lacking brightness, fused with 'wit,' the old word for the mind's sharpness or intelligence (as in 'keep your wits about you'). Put them together and you get a mind whose light is turned down low — the same dimness-as-stupidity logic behind cousins like 'dim bulb' and 'not too bright.'

origin
Dim meaning dull, wit meaning mind, 1920s slang
not clinical
Insult, not a diagnosis, despite confident usage
cousin words
Nitwit, halfwit, dullard, all basically siblings
ironic twist
Calling someone one rarely requires much wit either
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