To form curds so that it no longer flows smoothly; to cause to form such curds. (usually said of milk)
To cause a liquid to spoil and form clumps so that it no longer flows smoothly
To clot or coagulate; to cause to congeal, such as through cold. (metaphorically of blood)
To make homogeneous, to blend or puree.
Specifically, to treat milk so that the cream no longer separates.