What does "curdle" mean?

Curdle: To thicken; to congeal. Then Mary could feel her heart's blood curdle cold. Southey.

Additional senses

  1. 2.To change into curd; to cause to coagulate. "To curdle whites of eggs" Boyle.
  2. 3.To congeal or thicken. My chill blood is curdled in my veins. Dryden.

Sources