not know the time of day

To be completely unintelligent, daft, or not alert. We paid for her to attend the best university in the state, but three years in, she still doesn't know the time of day. How can you expect me to respect my boss when he doesn't even know the time of day?

know the time of day

be well informed about something.

See also: know, of, time

Farlex Partner Idioms Dictionary © Farlex 2017

See also:

know the time of day
slow study
(as) daft as a brush
daft
daft as a brush
dim
dim bulb
fish
fish-fight

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