When Judah saw her, he thought her to be an harlot; because she had covered her face. Thought her to be a harlot - See the original of this term, Genesis 34:31 (note). The Hebrew is זונה zonah, and signifies generally a person who prostitutes herself to the public for hire, or one who lives by the public; and hence very likely applied to a publican, a tavern-keeper, or hostess, Joshua 2:1; translated by the Septuagint, and in the New Testament, πορνη, from περναω, to sell, which certainly may as well apply to her goods as to her person.
It appears that in very ancient times there were public persons of this description; and they generally veiled themselves, sat in public places by the highway side, and received certain hire. Though adultery was reputed a very flagrant crime, yet this public prostitution was not; for persons whose characters were on the whole morally good had connections with them. But what could be expected from an age in which there was no written Divine revelation, and consequently the bounds of right and wrong were not sufficiently ascertained? This defect was supplied in a considerable measure by the law and the prophets, and now completely by the Gospel of Christ.