[1875–80; offside + -er1]This word is first recorded in the period 1875–80. Other words that entered Englishat around the same time include: cross-fertilization, massage, neoclassic, pressure point, slime mold-er is a suffix used in forming nouns designating persons from the object of their occupationor labor (hatter; tiler; tinner; moonshiner), or from their place of origin or abode (Icelander; southerner; villager), or designating either persons or things from some special characteristic or circumstance(six-footer; three-master; teetotaler; fiver; tenner).