late 14c., prevaricacioun, "divergence from a right course, transgression, violation of a law or commandment" (a sense now obsolete), from Old French prevaricacion "breaking of God's laws, disobedience (to the Faith)" (12c., Modern French prévarication) and directly from Latin praevaricationem (nominative praevaricatio) "duplicity, collusion, a stepping out of line (of duty or behavior)," noun of action from past-participle stem of praevaricari "to make a sham accusation, deviate," literally "walk crookedly," in Church Latin, "to transgress."
This Latin word is from prae "before" (see pre-) + varicare "to straddle," from varicus "straddling," from varus "bowlegged, knock-kneed" (see varus). The main modern meaning "evasion, quibbling, act of deviating from truth, honesty, or plain dealing" is attested from 1650s.