adj. hap·pi·er, hap·pi·est
1. Enjoying, showing, or marked by pleasure, satisfaction, or joy: a happy child; the happiest day of my life. See Synonyms at glad.
2. Cheerful; willing: happy to help.
3. Characterized by good luck: a happy sequence of events. See Synonyms at fortunate.
4. Being especially well-adapted; felicitous: a happy turn of phrase.
a. Characterized by a spontaneous or obsessive inclination to use something. Often used in combination: trigger-happy.
b. Enthusiastic about or involved with to a disproportionate degree. Often used in combination: money-happy; clothes-happy.
[Middle English, from hap, luck; see HAP.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.