preposterous [M16th] The Latin word praeposterus meant both ‘reversed, back to front’, and ‘absurd’, combining prae ‘before’ and posterus ‘coming after’. When the English word entered the language it had a pair of meanings that mirrored those in the Latin. One of these, ‘having last what should be first’, is very rare now. But the other, describing anything that seems contrary to reason or absurd, is still going strong.