“Spay/neuter” is shorthand for the surgery performed by a veterinarian on a dog or cat to prevent the animal from reproducing. Technically, a female is “spayed” and a male is “neutered,” but the terms are often used interchangeably. “Fixing” and “altering” are other common terms used for spay/neuter.
The spay procedure, also known as an ovariohysterectomy, removes the uterus and ovaries. Neutering, also known as castration, removes the testicles. Spay/neuter permanently sterilizes the animal.