What does "defeat" mean?

Defeat: To render null and void, as a title; to frustrate, as hope; to deprive, as of an estate. He finds himself naturally to dread a superior Being that can defeat all his designs, and disappoint all his hopes. Tillotson. The escheators . . . defeated the right heir of his succession. Hallam. In one instance he defeated his own purpose. A. W. Ward.

Additional senses

  1. 2.To overcome or vanquish, as an army; to check, disperse, or ruin by victory; to overthrow.
  2. 3.To resist with success; as, to defeat an assault. Sharp reasons to defeat the law. Shak.
  3. 4.An undoing or annulling; destruction. [Obs.] Upon whose property and most dear life A damned defeat was made. Shak.
  4. 5.Frustration by rendering null and void, or by prevention of success; as, the defeat of a plan or design.
  5. 6.An overthrow, as of an army in battle; loss of a battle; repulse suffered; discomfiture; -- opposed to victory.

Sources