Whether it is the cardinal sin, or the (cuddly?) slow-moving animal, there is a question mark over its pronunciation. On this morning’s edition of Saturday Live on BBC Radio 4, the well-known ‘sloth-woman’, Lucy Cooke, was interviewed. She always says the name to rhyme with ‘moth’, because, as she says, there is a moth that lives on the sloth, and this is the /slɒθ mɒθ/, not the /sləʊθ məʊθ/. Obviously this is a silly argument, as we all know that spelling in English is so apparently inconsistent that there is no reason why it should not be a /sləʊθ mɒθ/. She further said that she distinguished it from the sin, which she pronounced /sləʊθ/. A listener texted, or tweeted, that as the animal was named for the sin, this argument was also unsatisfactory. Then Sir David Attenborough got in on the act, letting the programme known that he always called both the animal and the sin /sləʊθ/. The Oxford English Dictionary was also quoted, and this has /sləʊθ/ as the usual British pronunciation, but /slɔθ, sloʊθ, slɑθ/ the American (given in that order, presumably of frequency heard).

I have always said /sləʊθ/. The etymology of ‘sloth’ is the adjective ‘slow’ plus the nominalizing suffix ‘-th’, as in ‘width, breadth, depth, length, warmth, coolth’. It seems that the vast majority of these  have a short vowel which is derived from a long vowel in the root adjective. Whatever the form in Middle English, therefore (the OED’s earliest example is from ca 1175 – ‘slauðe’), there must be a strong analogical pull in ‘sloth’ towards shortening its vowel too. Added to which, more of the words ending in –oth have a short vowel: broth, cloth, Goth, moth, the Egyptian god Thoth, while both and loth are the only other words to come to mind immediately with /əʊ/. The loss of the letter ‘w’ has made us forget the word’s compound morphological origins.


  1. The other -th words (“breadth”, “strength”, etc) all derive from adjectives that end in consonants, unlike “slow”.

  2. dw – I’m sure you’ve got the right explanation for the historical long vowel in ‘sloth’ (and perhaps if we’d retained the ‘w’ in the spelling, we wouldn’t be having this conversation). However, this shortening of the vowel before a consonant must have been lost as a productive mechanism a long time ago, as ‘coolth’, with its equally long vowel, has been recorded, albeit not commonly, since the 16th century. The OED does not, to my eyes at least, make a clear connexion between ‘cool’ and ‘cold’, although they are obviously related.

  3. That many General British speakers call it /slɒθ/ should hardly be surprising when one considers that, whereas only the word both rhymes the other version of sloth (‘Thoth’ is ‘obscure’). On the spelling ‘loth’ versus ‘loath’ surely the latter is much the commoner. ‘Loathsome’ is exclusively spelt with ‘oa’. Brits may be influenced by not only cloth, froth, Goth and moth, but also the polysyllables apothecary, brothel, Gothenburg, Gothic, and hypothesis. In his Longman Pronunciation Dictionary Wells labelled \slɒθ\ as ‘non-RP’ though he accorded ‘RP’ status to the \trɒθ\ variant of troth. Webster dictionaries give first the version with the vowel they have in ‘law’ and second the one they have in ‘low’.

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