Slump, v. i. [imp. & p. p.Slumped (?); p. pr. & vb. n.Slumping.] [Scot. slump a dull noise produced by something falling into a hole, a marsh, a swamp.] To fall or sink suddenly through or in, when walking on a surface, as on thawing snow or ice, partly frozen ground, a bog, etc., not strong enough to bear the person.
The latter walk on a bottomless quag, into which unawares they may slump. Barrow.