na-adjective
dogmatic; arbitrary; high-handed
Describes a person, decision, or attitude that is based on personal opinion without considering others' views or evidence. Often carries a negative connotation of being overbearing or unilateral.
彼の独断的なやり方にみんな反対した。
Everyone opposed his arbitrary way of doing things.
上司
The project was canceled due to the boss's dogmatic decision.
独善的 emphasizes self-righteousness or believing one's own way is correct, whereas 独断的 focuses on making decisions alone without consulting others.
Compound of 独断 (arbitrary decision) + 的 (adjectival suffix). 独断 itself is from 独 (alone) and 断 (decide).