Showing smug or uncritical satisfaction with oneself or one's achievements; self-satisfied in a way that prevents further effort or improvement. Often implies dangerous overconfidence.
From Latin 'complacere' meaning 'to be very pleasing,' from 'com-' (intensive) and 'placere' (to please). The word evolved from meaning 'pleased' to implying excessive self-satisfaction.
Don't confuse with 'complaisant' (eager to please others)! Complacent people are pleased with themselves - they're so satisfied they stop trying. Think of someone lounging comfortably, too pleased to get up and work harder.
Complete word intelligence in one call. Free tier — 50 lookups/day.