"comfort in grief; that which brings consolation," c. 1300, solas , from Old French solaz "pleasure, entertainment, enjoyment; solace, comfort," from Latin solacium "a soothing, assuaging; comfort, consolation," from solatus , past participle of solari "to console, soothe," from a suffixed form of PIE root *selh- "to reconcile" (source also of Greek hilaros ).

Also 14c.-15c. sometimes solaunce , with substitution of -ance suffix. To make solace in Middle English was "enjoy oneself sexually," also "give (a horse) a rest." The adjectival form solacious "pleasantly agreeable, affording comfort" was "common c 1500-1650" [OED].

"to comfort (someone), console in grief or trouble," late 13c., solasen , also in Middle English "entertain, amuse, please," from Old French solacier , solasser, "to comfort, console" (often with a sexual connotation) and directly from Medieval Latin solatiare "give solace, console" (source also of Spanish solazar , Italian sollazzare ), from Latin solacium (see solace (n.)). Related: Solaced ; solacer ; solacing .