not know the time of day

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?

See also: know, not, of, time

Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.

know the time of day

be well informed about something.

See also: know, of, time

Farlex Partner Idioms Dictionary © Farlex 2017