lash-up noun 1lash up verb 1forms 4 noun1 •(informal) A crude improvisation or bodged effort.The home-made raft was a lash-up, but it floated. lash up verb1 •(informal) To construct in a shoddy, makeshift manner.Of things not properly belonging to the room, there was a hammock lashed up, and thrown upon the floor in one corner; […] — 1851 formslashed up · lashing up · lashes up · lash-ups