costrel

cos·trel

C0674200 (kŏs′trəl)n. A flat, pear-shaped drinking vessel with loops for attachment to the belt of the user.
[Middle English, from Old French costerel, possibly from costier, at the side, from coste, rib, from Latin costa; see kost- in Indo-European roots.]

costrel

(ˈkɒstrəl) n (Brewing) obsolete a flask, usually of earthenware or leather[C14: from Old French costerel, from coste side, rib, from Latin costa]