a small woodland fern, Gymnocarpium dryopteris, of northern regions, having triangular, pinnate fronds that slant horizontally.
Origin of oak fern
1540–50; translation of Latin dryopteris < Greek dryopterís, equivalent to dryo- (combining form of drŷs oak) + ptéris fern
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for oak fern
a graceful light green polypody fern, Thelypteris dryopteris, having a creeping rhizome, found in acid woodlands and on rocks in the northern hemisphere
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