[ʊ] is a short vowel sound, as in good or wolf or bush. Is there at least one word which starts with it in English?
(UK) IPA(key): /ˈʊm.laʊt/, /ˈʌm.laʊt/
(US) IPA(key): /ˈʊm.laʊt/, /ˈum.laʊt/
Oopsy-daisy (AmE) starts with /ʊ/. And I think it counts as a word—it's in the dictionary.