noun Cell Biology.
the period of the cell cycle prior to mitosis, during which the chromosomes are replicated.
Origin of S phase
First recorded in 1940–45
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
The phase of the mitotic cycle during which DNA synthesis occurs.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.