- A small mass of matter of irregular shape; an irregular or shapeless mass; as, a lump of coal; a lump of iron ore. "A lumpof cheese."Piers Plowman."This lumpof clay." [Shak.]
- A mass or aggregation of things.
- [Firearms] A projection beneath the breech end of a gun barrel.
Etymology: Cf. OD. lompe piece, mass. Cf. Lunch