13-letter words ending in I

Staphylococci, anthropophagi and scaphocephali show the shape: a classical plural with an I at the end. Only O, X and K close fewer thirteen-letter words, and just seven of these thirteen appear in NWL2023. Two entries, manrikigusari and tsutsugamushi, come from Japanese instead.

The I ending, word by word

• 13 thirteen-letter words end in I, the fifteenth-largest closing group at this length.
• All 13 are in Collins, while NWL2023 and ENABLE take 7 each.
• Three tie at the top on 27 points: staphylococci, conversazioni and scaphocephali.
• None counts as common English, and eight carry a dictionary definition.
• A and S open three words each, M and P two each.

Why every one of these ends in a vowel

Latin and Greek plurals drop a final -us or -um and replace it with -i. Staphylococci, pneumobacilli, actinobacilli and proventriculi all follow that rule, and four of the thirteen words carry a doubled letter somewhere.

Italian supplies four more: conversazioni, aggiornamenti, improvisatori and maccheroncini. The grammar is the same, a plural -i where English would add an S, which is why the endings look identical across two languages.

Only manrikigusari and tsutsugamushi break the European pattern. One names a Japanese weapon, the other a mite, and neither takes an English plural in -s.

Scores run high for such a small list

staphylococci, conversazioni and scaphocephali all reach 27, and that is the ceiling here. The average is 21.8, above the 20.4 for thirteen-letter words as a whole.

The tiles explain it. This group leans on C, Y and P rather than the flat A and E that fill most long lists, so even an obscure plural returns a workable score.

Six of the thirteen sit in Collins but not in NWL2023, so nearly half the list disappears in North American play. maccheroncini, manrikigusari and scaphocephali are Collins-only examples.

How to use a list this small