pleased, esp. with oneself or one's merits, advantages, situation, etc., often without awareness of some potential danger or defect; self-satisfied: The voters are too complacent to change the government.
2.
pleasant; complaisant.
Origin: 1650–60; < L complacent- (s. of complacēns, prp. of complacēre to take the fancy of, please, equiv. to com-com-+ placēre to please
Contented to a fault; self-satisfied and unconcerned: He had become complacent after years of success.
Eager to please; complaisant.
[Latin complacēns, complacent-, present participle of complacēre, to please : com-, intensive pref.; see com- + placēre, to please; see plāk-1 in Indo-European roots.] com·pla'cent·ly adv.