An Etymological Dictionary of the Scottish Language / in which the words are explained in their different senses, authorized by the names of the writers by whom they are used, or the titles of the works in which they occur, and deduced from their originals

by John Jamieson

Lounfow, adj. Rascally, S.

Loun-like, adj.
1. Having the appearance of a loun, S.
Ross.
2. Shabby; applied to dress, S.

Lounrie, s. Villany.
Dunbar.

LOUN, LOWN, s. A boy, S.
Dunbar.

Isl. lione, servus.

Loun's piece, the uppermost slice of a loaf of bread, S.

To LOUNDER, v. a. To beat with severe strokes, S.
V. [Loundit].
Ramsay.

Lounder, s. A swinging stroke, S.
Watson.

LOUNDIT, part. pa. Beaten.
Dunbar.

This seems the origin of Lounder, apparently allied to Fenn. lyon, ferio, verbero.