(1):

(v. t.) To agitate; to affect mentally.

(2):

(v. i.) To become, in some respects, different; to vary; to change; as, the weather alters almost daily; rocks or minerals alter by exposure.

(3):

(v. t.) To make otherwise; to change in some respect, either partially or wholly; to vary; to modify.

(4):

(v. t.) To geld.