slipsole

[slip-sohl]

noun

an insole placed in a shoe for warmth or to adjust the size.
a thin strip of material, as leather, set between the insole and the outsole of a shoe, usually for height.

Origin of slipsole

First recorded in 1905–10; slip1 + sole2
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019