Fetching details from the dictionary...

to be lazy; to be idle; to slack
to neglect (e.g. one's work); to be neglectful of; to skip (e.g. school)
試験前なのに一週間も怠けた。
I slacked off for a whole week even though exams were coming up.
最近忙しくて勉強を怠けてしまっている。
I neglected my studies recently.
最近、弟は宿題をせずに怠けている。
Lately, my younger brother has been slacking off without doing his homework.