Tagmul appears only once in the Hebrew Bible (Psalm 116:12), in the psalmist's cry of gratitude: 'What shall I return to the LORD for all his benefits to me?' The word is derived from the root gamal (to deal with, to ripen, to wean — see H1580 gamal), which carries the meaning of completing or fulfilling something. Tagmul thus captures all the completed, fulfilled, abundant goodnesses God has poured out on His servant.
Psalm 116 is a profound meditation on rescue and gratitude — a psalm of thanksgiving for deliverance from death. The question of verse 12 ('What shall I return [tagmul] to the LORD?') is the heartbeat of covenant worship: recognizing the immeasurable weight of divine grace and asking how finite creatures can possibly respond. The psalmist answers with the cup of salvation, calling on the Name of the LORD, fulfilling vows, and offering sacrifices of thanksgiving. The New Testament counterpart is Romans 12:1 — offering your body as a living sacrifice is the 'reasonable worship' in response to God's mercies (tagmul).