Brethren has passed through three stages. The old plural was brothru, then brothre or brethre, finally brethren. The weakening of inflections led to this addition.
Children has passed through the same history, though the intermediate form childer lasted till the seventeenth century in literary English, and is still found in dialects; as,—
"God bless me! so then, after all, you'll have a chance to see your childer get up like, and get settled."—Quoted By De Quincey.
Kine is another double plural, but has now no singular.
In spite of wandering kine and other adverse circumstance.—Thoreau.
II. Plurals formed by Vowel Change.
40. Examples of this inflection are,—
- man—men
- foot—feet
- goose—geese
- louse—lice
- mouse—mice
- tooth—teeth
Some other words—as book, turf, wight, borough—formerly had the same inflection, but they now add the ending -s.
41. Akin to this class are some words, originally neuter, that have the singular and plural alike; such as deer, sheep, swine, etc.