IPA: /ˈpɪloʊˌkeɪs/
KK: /ˈpɪloʊˌkeɪs/
A cover that you put on a pillow to protect it and make it look nice.
I bought new pillowcases to match my bedspread.
Pillowcase → It is formed from "pillow" (from Old English *pyle*, meaning a cushion or support for the head) and "case" (from Latin *casa*, meaning a house or shelter). The word "pillowcase" refers to a covering or case for a pillow, providing protection and comfort for the head while sleeping.
Think of a 'case' that serves as a 'shelter' for your 'pillow' — that's why a pillowcase is a protective covering for your pillow.
No commonly confused words.