abnegar

To deny oneself something, usually for the sake of others — most often used reflexively (abnegarse) and much more commonly encountered as the noun abnegación (self-sacrifice, selflessness), a quality often praised in mothers, caregivers, and the devoutly religious.

• Se abnegó por completo al cuidado de sus padres. — She gave herself over completely to caring for her parents.
• Supo abnegarse en beneficio de la familia. — He knew how to deny himself for the family's benefit.
• Pocos están dispuestos a abnegarse tanto por otros. — Few are willing to sacrifice so much of themselves for others.

Learners are more likely to need the noun abnegación than to conjugate this verb — it's a formal, somewhat literary word, not something used casually in daily conversation.

Often confused with sacrificarse.