"comfort in grief, consolation," late 13c., 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). Adjectival form solacious is attested 16c.-17c.
"comfort, console in grief," late 13c.; also in Middle English "entertain, amuse, please," from Old French solacier "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; solacing.