noun
ambition to succeed in life; desire for career advancement
Refers to a strong personal drive to rise in status, rank, or worldly success. Often used in discussions of motivation or personality.
彼は出世欲が強く、いつも昇進を狙っている。
He has a strong ambition to succeed and is always aiming for promotion.
出世欲に駆られて、彼女は休日も働いている。
Driven by her desire to get ahead, she works even on her days off.
野心 is a broader term for 'ambition' that can be positive or negative, whereas 出世欲 is specifically about career or social advancement.
Compound of 出世 (success in life) and 欲 (desire). The exact historical derivation is uncertain, but the meaning is transparent from its components.