Someone who dips something into a liquid; also, a basketball player who dunks, or a member of the Dunkard sect.
From the verb 'dunk' (to dip into liquid) plus agent suffix '-er'. 'Dunk' itself comes from German/Dutch 'dunken' (to dip). In basketball slang, it emerged in the 1960s.
The word 'dunker' completely changed meaning within 50 years—from a religious sect member to a basketball move—showing how sports terminology can overshadow and eventually replace older historical meanings.
Complete word intelligence in one call. Free tier — 50 lookups/day.