a piece of soft material used by a doctor, nurse, etc. for cleaning wounds or taking a sample from somebody’s body for testing （医用的）拭子，药签 an act of taking a sample from somebody’s body, with a swab 用拭子对（人体）化验标本的采集 to take a throat swab 用棉签从咽部采集化验样品
Word Originmid 17th cent. (in the sense ‘mop for cleaning the decks’): back-formation from swabber ‘sailor detailed to swab decks’, from early modern Dutch zwabber, from a Germanic base meaning ‘splash’ or ‘sway’.