IPA: /kəmˈpleɪsənt/
KK: /kəmˈpleɪsənt/
Feeling satisfied with oneself and not worried about potential problems or dangers.
After winning the championship, the team became complacent and stopped training hard.
Complacent → It is formed from "com-" (meaning with or together) and "placere" (meaning to please). The word describes a state of being pleased with oneself, often to the point of being unaware of potential dangers or deficiencies.
Think of being 'pleased' ('placere') with yourself 'together' ('com-') — that's why complacent means being self-satisfied.