early 16th century (earlier (late Middle English) as alternation): from Latin alternat- ‘done by turns’, from alternare, from alternus ‘every other’, from alter ‘other’
16世紀初頭(それ以前は中世英語後期のalternation):ラテン語のalternat-「交代で行う」、alternareから、alternus「あらゆる他の」、alter「他の」からの由来。