"A widow... he not marry"—Leviticus 21:14.
A High Priest is forbidden to marry a widow.
(Actually, it is forbidden for a High Priest to have sexual relations with a widow—even without marriage. Thus, if he marries a widow and has relations with her, he transgresses two prohibitions.)
"Neither shall he profane his seed among his people"—Leviticus 21:15.
It is forbidden for a High Priest to have sexual relations with a widow.
"He shall marry a woman in her virgin state"—Leviticus 21:13.
A High Priest is commanded to marry a virgin.
"Neither shall they take a woman divorced by her husband"—Leviticus 21:7.
It is forbidden for a priest to marry a divorcee.
"They shall not take a wife who is a zonah"—Leviticus 21:7.
A priest may not marry a woman who in the past had sexual relations with a man whom she is forbidden to marry [e.g. a non-Jew or next of kin].
"They shall not take a wife who is... profaned"—Leviticus 21:7.
A priest may not marry a chalalah [a woman who in the past had sexual relations with a priest whom she is forbidden to marry because of his priestly status (e.g., she was a divorcee)], or the daughter born from a relationship between a priest and a chalalah.