to cause (milk or a soft mixture) to separate into solid curds or lumps and liquid
Any acid curdles milk
to cause (any liquid or soft mixture) to break up in this manner
to separate in this manner into curds or lumps and liquid
Add the egg, alternately with the flour, to prevent the mixture from curdling
make one's blood curdle
to fill one with dread
[frequentative of obsolete curd to thicken or congeal, from curd]