[1805–15, Amer.; anti- + union]This word is first recorded in the period 1805–15. Other words that entered Englishat around the same time include: backlash, makeup, one-sided, polarization, souffléanti- is a prefix meaning “against,” “opposite of,” “antiparticle of,” used in the formationof compound words (anticline); used freely in combination with elements of any origin (antibody; antifreeze; antiknock; antilepton)