curdle

verb
cur·​dle | \ ˈkər-dᵊl How to pronounce curdle (audio) \
curdled; curdling\ ˈkərd-​liŋ How to pronounce curdling (audio) , ˈkər-​dᵊl-​iŋ \

Definition of curdle

intransitive verb

1 : to form curds also : to congeal as if by forming curds a scream curdled in her throat
2 : to go bad or wrong : spoil

transitive verb

1 : to cause curds to form in curdled milk
2 : spoil, sour