Top, Help, Feedback, Customize Type in a word below to find its rhymes, synonyms, definitions, and more: Word:  Find rhymes Find synonyms Find antonyms Find definition Appears in definition of Find related words Find similar sounding words Find homophones Check spelling of word Match consonants only Match these letters Search in Shakespeare Search for quotations Organize results by: Syllables Letters     Include phrases: Yes No Rhymes   Synonyms   [Definitions]   Homophones   Similar sound   Same consonants   Related Definitions of activation energy: noun:   the energy that an atomic system must acquire before a process (such as an emission or reaction) can occur Search for activation energy at other dictionaries: OneLook, Answers.com, Merriam-Webster Search for activation energy:    [Definition]   Quotes   Encyclopedia   Copyright © 2010 Datamuse