lie-in noun 2lie in verb 2forms 5 noun2 •(UK) A period spent lying in bed for longer than usual after one has woken up.Since I didn't have to go to work, I decided to have a lie-in. •A form of protest where a group of people lie down in a public area. lie in verb2 •(UK) To stay in bed (longer than usual).I've got a day off tomorrow, so I might lie in till about 11. •(no longer used) To be brought to bed in childbirth.he had been driven to it by the distress he mentioned, the greatest indeed imaginable, that of five hungry children, and a wife lying in of the sixth, in the utmost want and misery. — 1749 formslay in · lain in · lying in · lies in · lie-ins