Something that sinks, or in baseball, a pitch that drops suddenly making it hard to hit.
From Old English 'sincan' (to sink) plus '-er' suffix meaning 'one who does.' In sports, it named the distinctive dropping motion of the pitch.
A sinker pitch in baseball is literally a pitch that sinks—pitchers throw it at the top of the strike zone but gravity and spin make it plummet, tricking batters into hitting weak ground balls.
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