phone case; smartphone case
Common everyday term for a protective or decorative case for a smartphone.
新しいスマホケースを買った。
I bought a new phone case.
このスマホケースは手帳型です。
This phone case is a folio type.
Variant with interpunct, sometimes used for clarity or in product names.
Wasei-eigo (Japanese-made English) combining スマホ (sumaho, 'smartphone') and ケース (kēsu, 'case').