Indicates spatial position (behind) or temporal sequence (after, afterward). In its verbal form, it conveys the act of following — whether physically trailing behind someone, or spiritually pursuing a path. The word frequently appears in covenantal contexts: Israel is called to walk after the LORD (Deut 13:4) but is warned against going after other gods.
The theological significance of ʾachar lies in its use to describe spiritual allegiance. To go 'after' (ʾacharê) the LORD is the essence of covenant faithfulness (1 Kings 18:21). To go 'after' other gods is the essence of apostasy (Deut 6:14). The word frames the fundamental human choice: Whom will you follow? Elijah's challenge on Mount Carmel — 'If the LORD be God, follow (ʾacharâv) him' — distills this theology. The word also carries eschatological weight: the ʾacharîth (end, latter days) derives from this root, pointing to what comes after — the final consummation of God's plan.