1. a combining form meaning “shining,” “appearing, seeming,” used in the formation of compound words: phenocryst.
  2. a combining form used in the names of chemical compounds that contain phenol or the phenyl group, are related to aromatic compounds, or derive from benzene: phenobarbital.
Also especially before a vowel, phen-.

Origin of pheno-

< New Latin phaeno- < Greek phaino- shining, combining form of phaínein to shine, appear; in chemical senses, used orig. with reference to products from the manufacture of illuminating gas Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for pheno-


before a vowel phen-

combining form
  1. showing or manifestingphenotype
  2. indicating that a molecule contains benzene ringsphenobarbital

Word Origin for pheno-

from Greek phaino- shining, from phainein to show; its use in a chemical sense is exemplified in phenol, so called because originally prepared from illuminating gas
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for pheno-

before vowels phen-, word-forming element in science meaning "pertaining to or derived from benzene," from phene.

Online Etymology Dictionary, © 2010 Douglas Harper

pheno- in Medicine


  1. Showing; displaying:phenotype.
  2. Relating to or derived from benzene:phenol.
  3. Containing phenyl:phenothiazine.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.