innersole

noun

1. An insole; a cushioning layer lining the inside bottom of a shoe or boot.

   “After his toe was severed in an accident, he had to buy orthopedic innersoles for his shoes.”

   “The slipsole is examined to determine whether it must be replaced or whether a patch is sufficient. Shoes which are worn through the bottom filler and/or innersole cannot be economically repaired.”