Strong's Definition
a primitive root of doubtful meaning; used only as a denominative from 2993; to marry a (deceased) brother's widow
KJV Usage: perform the duty of a husband's brother, marry
STEPBible — Tyndale Abridged Hebrew Lexicon
יָבַם (ya.vam) — be brother-in-law. 1) (Piel) to perform levirate marriage, perform the duty of a brother-in-law 1a) the duty due to a brother who died childless - to marry his widow and have a son for his name
UBS Dictionary of Biblical Hebrew
verb · יָבָם · יְבָמָה
Copulate | verb pi
to fulfill the duty of producing an heir for one's brother = action by which a man has intercourse with the wife of his deceased brother, if the brother did not have a son before he died ► to enable a descendance from that brother and perhaps to assure a family for the widow
UBS Dictionary of Biblical Hebrew © United Bible Societies, licensed CC BY-SA 4.0.
Brown-Driver-Briggs Hebrew Lexicon
[יָבַם] vb. denom., only Pi. do duty of יָבַם to a brother's widow base