Definition of "bloomers"

Fanny, knowing this, had made up her mind to go straight to Horn & Udell. Now, Horn & Udell are responsible for the bloomers your small daughter wears under her play frock, in place of the troublesome and extravagant petticoat of the old days.

1917, Edna Ferber, Fanny Herself‎

Moreover, the family realized perfectly that Alix would have clipped her thick hair, and taken to bloomers or knickerbockers outright, […]

c. 1920, Kathleen Thompson Norris, Sisters‎

Yet so radioactive were her nerves […] that she was more energetic than any of the hulking young women who, with calves bulging in heavy-ribbed woolen stockings beneath decorous blue serge bloomers, thuddingly galloped across the floor of the “gym” in practise for the Blodgett Ladies' Basket-Ball Team.

1920, Sinclair Lewis, chapter 1, in Main Street: The Story of Carol Kennicott, New York, N.Y.: Harcourt, Brace and Howe

Ladies’ grey flannelette bloomers, three shillings a pair, astonishing bargain. Plain and loved, loved for ever, they say.

1922 February, James Joyce, Ulysses, Paris: Shakespeare and Company, […]