Slop

According to the Old English Dictionary:

slop

a loose, upper garment. 'Slop a smock-frock; any kind of outer garment made of linen, ' Halliwell's Dict. [These cuttid sloppis or anslets, that thurgh her schortness ne covereth not the schamful membres of men. Chauc. Pers. T. Sloppe, garment mutatorium. Prompt. ParIcel. sloppr a gown, a loose garment, esp. a priest's gown.] v. ofer-slop, and cf. slípan, slype. slop

Related words: 460, col. 1.