Leviticus 21:14 Commentary - Ellicott's Commentary for English Readers (Old and New Testaments)

(14) A widow.—By this the high priest was not only forbidden to marry the widow of an ordinary Israelite, or even the widow of a priest, but, according to the Jewish canons, a virgin who had been betrothed to another man, and whom she lost by death before they were married. If he, however, became engaged to a widow before he was elected to the pontificate, he could marry her after his consecration. He was, however, exempt from the obligation to marry the widow of his brother who died without issue. (See Lev. 18:16.)

Or a divorced woman.—The classes of women which follow are also forbidden to the ordinary priests. (See Lev. 21:7.)