bootee

noun

1. A soft, woolen shoe, usually knitted, for a baby or small pet.

   “Take off the baby's bootees before you put her in the crib.”

   “‘No,’ said Luke, grinning at her. ‘You're not dull enough! […] What about the kid's clothes? I don't suppose they were anything to write home about, but didn't you keep anything? A bootee or a bit of embroidery or anything at all?’”

2. A thick sock worn under a wetsuit.
3. An overshoe or sock worn to cover dirty shoes or feet.

   “Surgeons often slip on bootees before entering the operating room.”

   “Just above the Sunset Strip, construction workers in white bootees were putting the final touches on another home — a 14,000-square-foot house that Mr. Niami is building for himself.”