a feeling of quiet pleasure or security, often while unaware of some potential danger, defect, or the like; self-satisfaction or smug satisfaction with an existing situation, condition, etc.
2.
Archaic.
a.
friendly civility; inclination to please; complaisance.
1436, from M.L. complacentia "satisfaction, pleasure," from L. complacentem (nom. complacens), prp. of complacere "to be very pleasing," from com- intensive prefix + placere "to please." Sense of "pleased with oneself" is 18c.