Boyd’s Bible Dictionary:
(vagabond). An abandoned woman (Gen. 38:15). Harlotry forbidden (Lev. 19:29). Type of idolatry (Isa. 1:21; Ezek. 16). Classed with publicans (Matt. 21:32).
Concise Bible Dictionary:
A woman given up to fornication: there were such as early as Genesis 38:15. The term is used metaphorically for unfaithfulness: “how is the faithful city become an harlot!” (Isa. 1:21; Ezek. 16:31,35). The mystic Babylon is designated “The mother of harlots” (Rev. 17:5), not only unfaithful herself, but the mother of such.