The question was prompted by trying to find an English analogue to the many words in Welsh that end with /ɒ/ (today's example: crwydro = wander). This sound is after all common in English at the beginning or in the middle of a word (ox, not).
I can't think of any common word in reasonably standard English that ends this way. As a Londoner originally I'm prone to t-glottalisation, which leads to something pretty close. Words spelt –o generally seem to end with the highly variable (so I haven't tried to give IPA) ɢᴏᴀᴛ vowel.
I'm approaching this from a Southern British perspective, but other common accents/dialects are also interesting. The original version of this question was confused by using IPA examples that were based on pronouncing cot to match caught but didn't say so explicitly.
So do any English words end with this sound?
Best Answer
In general, English words do not end with any of the stressed "short" vowel sounds (/ɒ/, /æ/, /ɛ/, /ʌ/, /ɪ/, /ʊ/). This is not an absolutely exceptionless rule: interjections may not follow it (for example, I have /æ/ in "yeah" and /ʌ/ in "duh"), and I don't find it particularly difficult to pronounce nonsense words ending in stressed /ɪ/, for example.
In American English, historical "short o" has been merged into the originally "long" vowel sound /ɑ/, so the original restriction on the distribution of the "short o" sound no longer applies, at least not on the surface level (the word spa ends in the same sound /ɑ/ that is used for the "short o" sound in pod, so pod and "spa'd" rhyme).
Furthermore, as far as I know there is no dialect of English where the sound /ɒ/ is in common use in fully unstressed open syllables. (Unlike /ɪ/ and /ʊ/, which some accents use in words like ready or gradual.)
So I don't think you'll be able to find any word ending in /ɒ/.
The symbol /ɔ/ is most commonly used in transcriptions of English to represent a vowel sound distinct from the sound of "short o". It is also transcribed /ɔː/ (with the IPA length marker "ː") in the context of British English to indicate that it functions as a "long vowel" in the British English vowel system. This vowel sound does occur word-finally, in various words spelled with -aw (law, claw, raw, straw), and in "non-rhotic" accents also in words spelled with -oar, -ore such as roar, more, tore, bore (and some words spelled with -oor such as door and floor).
The British English /ɒ/ phoneme ("short o") may be realized as the IPA phonetic vowel [ɔ], and the British English /ɔː/ phoneme may be realized as the IPA phonetic vowel [oː], but purely phonetic transcriptions are not very commonly encountered, particularly not when discussing restrictions on the distribution of sounds in a language's sound system. (Contrariwise, in American English the phoneme transcribed /ɔ/ may be realized phonetically as something like [ɒ]—even in accents where it is not merged with the open unrounded /ɑ/ sound, it often is relatively close to it phonetically.) This mainly comes up as an issue when people are trying to compare vowel sounds between different languages: for example, comparing English "o" sounds to those of Italian, French, or German.