Genetics. a protein that binds DNA at an operator site and thereby prevents transcription of one or more adjacent genes.

Nearby words

  1. represser,
  2. repressible enzyme,
  3. repression,
  4. repressive,
  5. repressively,
  6. repressor gene,
  7. reprieval,
  8. reprieve,
  9. reprimand,
  10. reprint

Origin of repressor

From Latin, dating back to 1955–60; see origin at repress, -tor


or re·pres·sor



a person or thing that represses.

Origin of represser

late Middle English word dating back to 1400–50; see origin at repress, -er1 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for repressor

British Dictionary definitions for repressor



biochem a protein synthesized under the control of a repressor gene, which has the capacity to bind to the operator gene and thereby shut off the expression of the structural genes of an operon
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

Medicine definitions for repressor




One that represses.
A protein, especially either of two proteins produced by regulatory genes, that blocks transcription of an operon.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for repressor



A protein that binds to an operator, blocking transcription of an operon and the enzymes for which the operon codes.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.