noun
Academic term referring to the branch of philosophy dealing with ethics and morality.
彼は大学で道徳哲学を専攻している。
He is majoring in moral philosophy at university.
倫理学 is the more common modern term for 'ethics' as an academic discipline, while 道徳哲学 is a slightly older or more traditional term for moral philosophy.
Compound of 道徳 (morals) and 哲学 (philosophy), a straightforward calque of the English term 'moral philosophy'.