IPA: /kəmˈpæʃənləs/
KK: /kəmˈpæʃənləs/
Lacking feelings of sympathy or concern for others.
His compassionless attitude made it difficult for him to connect with his colleagues.
Compassionless → It is formed from "compassion" (from Latin "compassio", meaning to suffer with) and "-less" (meaning without). The word "compassionless" means without compassion or lacking the ability to empathize with others' suffering.
Think of 'suffering with' ('compassio') and remember that 'compassionless' means lacking that ability to empathize.