| mutated plurals |
| Definition: Words whose internal vowels change to form their plural. |
| Example: English has seven such pairs: man/men, louse/lice, tooth/teeth, mouse/mice, goose/geese, foot/feet, and woman/women. |
| Oxford English Dictionary: The first OED citation of the concept (there is no entry for the exact phrase) is from 1875–6: "It is extremely probable that all subjunctives originally had mutated vowels." (H. Sweet in Trans. Philol. Soc. 549) |