Ūna (adj.) [Vedic ūna; cp. Av. ūna, Gr. eu)_nis, Lat. vāpus, Goth. wans, Ags. won = E. want] wanting, deficient, less M ii.73; J v.330; DhA i.77; DhA iv.210. Mostly adverbially with numerals = one less, but one, minus (one or two); usually with eka (as ekūna one less, e. g. ekūna -- aṭṭhasataŋ (799) J i.57; ekūna -- pañcasate KhA 91, ekūna -- vīsati (19) Vism 287; ekenɔūnesu pañcasu attabhāvasatesu (499) J i.167; also with eka in instr. as eken'ūnapañcasatāni (deficient by one) Vin ii.285; KhA 91; sometimes without eka, e. g. ūnapañcasatāni (499) Vin iii.284; ūnavīsati (19) Vin iv.130, 148. With "two" less: dvīhi ūnaŋ sahassaŋ (998) Ji.255. -- anūna not deficient, complete PvA 285 (= paripuṇṇa).
   -- udara (ūnudara, ūnūdara, ūnodara) an empty stomach, adj. of empty stomach; ˚udara J ii.293; vi.295; ˚ūdara 
J vi.258; Miln 406; odara Sn 707; DhA i.170. -- bhāva depletion, deficiency SnA 463 (v. l. hānabhāva).

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

ūna : [adj.] less; minus; wanting; deficient.

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

ūná mfn. (√av Uṇ. iii, 2

• ? Zd. ūna), wanting, deficient, defective, short of the right quantity, less than the right number, not sufficient

• less (in number, size, or degree), minus, fewer, smaller, inferior AV. x, 8, 15 ; 44 ; xii, 1, 61 TS. ŚBr. Mn. Ragh. &c

• less than (with abl., e.g. lakṣād ūna, less than a Laksha Kathās. liii, 10

• or ifc., e.g. tad-ūna, inferior to that one Mn. ix, 123), less by (with instr., e.g. dvābhyām ūna, less by two ŚBr. xi

• or ifc., e.g. alpôna, less by a little, a little less Mn.

• pañcôna, less by five &c.)

• less by one (prefixed to decimals from twenty up to one hundred, e.g. ūna-viṃśa =ekôna-viṃśa, the twentieth minus one, the nineteenth)

Sanskrit-English Dictionary, by M. Monier William