rattlebrain

plural rattlebrains

1. A rattlebrained person.

   My mother, peace be with her, when she called me a rattlebrain, was right.

   1962, Isaac Bashevis Singer, translated by Isaac Bachevis Singer and Cecil Hemley, The Slave, New York: Farrar, Straus & Giroux, published 1985, Part III, p. 297

   1 more example

   a genial young fellow enough to look at, and something of a rattlebrain, to all appearance.

   1924, Herman Melville, chapter 13, in Billy Budd, London: Constable & Co.