fern test

[fûrn]
n.
  1. A test for estrogenic activity in which cervical mucus smears form a fernlike pattern at times when estrogen secretion is elevated, as at the time of ovulation.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.