To tell someone to do something; to order or instruct someone (often used as 'tell someone to ~').
母は子どもに部屋を片付けるよう言いつけた。
The mother told her child to clean the room.
上司が私に資料を明日までに提出するよう言いつけた。
My boss told me to submit the documents by tomorrow.
先生は係の学生に放送の準備を言いつけた。
The teacher instructed the student in charge to prepare the broadcast.
To tell on someone; to report or snitch on someone to an authority or parent.
彼はクラスメートのいたずらを先生に言いつけた。
He told the teacher about his classmate's prank.
子どもが友だちの行動を親に言いつけてしまった。
The child ended up telling the parents about a friend's behavior.
To say something habitually; to be in the habit of saying or telling (used in a habitual or customary sense).
母はいつも『出かけるときは電気を消しなさい』と言いつける。
My mother always tells me, 'Turn off the lights when you go out.'
彼は会うたびに同じ忠告を言いつけるので、少し困っている。
He gives the same piece of advice every time we meet, which is a bit troublesome.