Lousy means very bad indeed, said informally. A lousy film, feel lousy, lousy weather.
It also means feeling ill — I feel lousy — which is a distinct sense. Lousy with means full of, usually of something unwelcome: lousy with tourists. The origin is literal and unpleasant: lousy meant infested with lice, and the figurative sense grew out of that.
1adjectivelousyVery bad indeed.
“The food was lousy and the service was even worse.”
2adjectivefeelingFeeling ill.
“I feel lousy; I think I'm getting a cold.”
lousy is a quality of badness.
Middle English lousy is louse plus -y, and first meant infested with lice. The sense of very bad grew from it.
Middle English
lousy
English, today
lousy
From Middle English lousy, lowsy, lousi, equivalent to louse + -y.
Etymology from Wiktionary, CC BY-SA