Complacent describes someone who is too satisfied with themselves and has stopped worrying about problems, often to their own cost. Complaisant describes someone who is eager to please other people, agreeable and obliging. A complacent manager ignores warning signs because things have gone well; a complaisant assistant goes along with whatever the boss wants.
The core difference
Complacent means smugly self-satisfied and blind to risk, while complaisant means willing to please others and agreeable.
- complacent — too pleased with oneself or one's situation, ignoring real risks: The team grew complacent after several easy wins and then lost badly.
- complacent — Don't get complacent just because sales are up this quarter.
- complaisant — willing to do what pleases others; obliging and agreeable: He kept a complaisant staff who never questioned his decisions.
How to tell them apart
Despite the near-identical spelling, these words point in different directions. Complacent is about your own attitude towards yourself: you feel satisfied and stop being alert to danger. It is almost always used as a warning, as in the phrase to grow complacent, meaning to let your guard down.
Complaisant is about your attitude towards other people: you go along with what they want, politely and obligingly. It is a much rarer word today, so if you are unsure which one a sentence needs, complacent is by far the more likely candidate in modern writing; reach for complaisant only when you specifically mean someone is being accommodating to others.
