1 : bad or poor
She got lousy grades in high school.
I like the work, but the pay is lousy.
He was a lousy husband.
: of poor quality : not good or skillful
They did a lousy job.
a lousy cook/driver
a lousy performance
— often + at or with
He is lousy [=terrible] at sports/math/cooking.
She's lousy with kids.
2 : not well or healthy
We could see that she was feeling lousy. [=feeling ill]
He drank too much and felt lousy the next morning.