tumba : [m.; nt.] a kind of water-vessel; a measure used for grain.

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

Tumba (m. nt.) [possibly=Sk. tumra swollen (of shape), same root as tumula] 1. a kind of water vessel (udaka˚ DA i.202), made of copper, wood or a fruit (like a calabash, cocoanut, etc., cp. kaṭāha, E. skull) Vin i.205 (loha˚, kaṭṭha˚, phala˚); ii.114 (˚kaṭāha of gourd); J iii.430 (udaka˚); iv.114; DhA ii.193 (udaka˚). -- 2. a measure of capacity, esp. used for grain J i.233 (mahā˚), 467 (=4 nāḷi p. 468); Miln 102.

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