A spatial and relational preposition meaning 'between' two parties, objects, or concepts. Related to the verb bîn (H995, to understand, discern), it carries the nuance of distinguishing — to see 'between' things is to discern their difference. It frequently marks covenantal relationships (between God and man) and judicial distinctions (between clean and unclean, holy and common).
The connection between bêyn (between) and bîn (understanding) reveals a deep Hebrew insight: wisdom is the ability to distinguish. Priests were charged with teaching Israel to discern between holy and common, clean and unclean (Lev 10:10; Ezek 44:23). Covenants are made between parties (Gen 9:12; 17:2), and God's rainbow sign is set between Himself and the earth. The word also marks the theological space where God meets humanity — He walks between the pieces of Abraham's covenant sacrifice (Gen 15:17), and the tabernacle is pitched in the midst of the camp. The discernment theme reaches its climax in Solomon's request for a 'hearing heart to judge… to discern between good and bad' (1 Kings 3:9).