This adjective describes people with divided hearts or double-minded attitudes, particularly in religious devotion. The psalmist declares passionate hatred for such half-hearted persons, loving God's law while despising those who treat it ambivalently. The term suggests internal division, wavering commitment, and unreliable character. It may derive from imagery of branching or splitting. The religious context indicates those who try to maintain competing loyalties rather than wholehearted covenant faithfulness.