Today at Futility Closet comes a report on the Mesembryanthemum:
The South African flower Mesembryanthemum draws its name from the Greek roots for middle, embryo, and flower. It’s believed to be the English word containing the highest “score” in Roman numerals — four Ms.
I have no quarrel with the first sentence but the second struck me as immediately improbable, because there are no other letters in Mesembryanthemum with a Roman numeral value so its total value is only 4000. I was immediately able to think of a couple that equal it – words that should be familiar to virtually anyone – and with a little searching was able to find a word that I knew and could define with a total of 4502 (Correction: 4602 – I should learn to add better). Can you find my word? More importantly, can you beat my word’s score?
Edit to add: The word is ‘IMMunoCoMproMIseD’, for a total of 4602, as one clever reader has discerned. This is just a game, of course, but there is a long tradition of Roman numeral chronograms in Europe, passages in which the sum of the Roman numerals gives a significant date. A multi-volume corpus of thousands of these was published in the 19th century and is practically begging for reanalysis – the inscriptions can be located and dated securely (Hilton 1882, 1885, 1895).
Hilton, James. 1882. Chronograms. London: Elliot Stock.
———. 1885. Chronograms Continued. London: Elliot Stock.
———. 1895. Chronograms Collected. London: Elliot Stock.
Glossographia 
Hmm, ‘antimuhammadanism’ would make 4,502, if we can consider that a word. How about ‘mammatocumuloid’? It’s real (it gets a google hit) and it weighs in at 4,651.
I’d rule (since it’s my game, I get to do so) that it has to appear in the Oxford English Dictionary to qualify, and neither of those are there. But I like the way you think!
It just occurred to me that one interpretation of the phrase “the highest “score” in Roman numerals” would be that the numerals have to occur in order. In that case, none of the words I’ve found higher than 4000 qualify. But I think this would be an inane interpretation, so I choose to ignore it.
Don’t forget, the OED doesn’t list all inflected forms, and it does have ‘mammatocumulus’, of which ‘mammatocumuloid’ would be a predictable and expected inflection.
True, although they’re actually pretty good with scientific terms in listing the major inflected forms. I’m only able to find one Google hit on ‘mammatocumuloid’, a jocular usage, not a scientific one.
Best I could find was ‘dynamometamorphism’ at 4501, and I can’t define it, but I do get about 21300 hits on google.
That’s a good one – it is in the OED. Still one short.
Hah! I’m pretty sure I found your word: ‘immunocompromised’ for 4602. I found a few higher scorers but I suspect they aren’t words:
HOMOSUMHUMANINILAMEALIENUMPUTO : 5103
I think this is just a Latin phrase, but I can’t tell for sure as my Latin isn’t good enough. The only Google hits appear to be word lists.
DEMI-MOHAMMEDAN / PSEUDO-MOHAMMEDANSIM : 5001
These appear to be real words but they have hyphens and so probably don’t count. I did manage to find the latter without the hyphen, but that seemed an unusual usage.
MARIEIMMACULESMOBLATDE / MARIEIMMACULEESEMOBLATDE : 4702
These appear to be Latin species names and so probably don’t count even if I could find them being used, which I can’t.
Yes, ‘immunocompromised’ is it, and it would help if I learned to add and give the correct total, which is, as you say, 4602, not 4502.
but surely the IMM in ‘IMMunoCoMproMIseD’, is 1,999 for a total of 4,600? :-)
rhb
I think this would be better if only Roman Numerals were used for the word such as LIVID, MIX, MIMIC, etc..AND they are scored as the numerals would be counted?