different between rattlebrain vs imbecile

English

Etymology

rattle +? brain

Noun

rattlebrain (plural rattlebrains)

1. A rattlebrained person.
   • 1924, Herman Melville, Billy Budd, London: Constable & Co., Chapter 13, [1]

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

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

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

English

Etymology

From Middle French imbécile, from Latin imb?cillus (“weak, feeble”), literally “without a staff”.

Pronunciation

• (Received Pronunciation) IPA^(key): /?mb??si?l/
• (General American) IPA^(key): /??mb?s?l/, /??mb?s?l/

Noun

imbecile (plural imbeciles)

1. (obsolete) A person with limited mental capacity who can perform tasks and think only like a young child, in medical circles meaning a person who lacks the capacity to develop beyond the mental age of a normal five to seven-year-old child.
2. (derogatory) A fool, an idiot.

Usage notes

• In modern times, “imbecile” is often used in jocular insults.

Synonyms

• See also Thesaurus:idiot

Derived terms

• imbecilic (adjective)
• imbecility (noun)

Translations

Adjective

imbecile (comparative more imbecile, superlative most imbecile)

1. (dated) Destitute of strength, whether of body or mind; feeble; impotent; especially, mentally weak.

   hospitals for the imbecile and insane