kosaka : [m.; nt.] a cup; drinking vessel; a small case or sheath.

A.P. Buddhadatta Mahathera, Concise Pali-English and English-Pali Dictionary [available as digital version from Metta Net, Sri Lanka]

Kosaka [fr. kosa] 1. a sheath for a needle J iii.282; - 2. a bowl, container, or vessel for food J i.349 (v. l. kesaka); M ii.6, 7, ( -- ˚āhāra adj. living on a bowl -- full of food; also aḍḍha˚) Vism 263. -- 3. case for a key (kuñcikā˚) Vism 251.

Pali-English Dictionary, TW Rhys Davids, William Stede,