oak fern

noun

: a widely distributed fern (Thelypteris dryopteris) of the family Polypodiaceae chiefly of damp acid woodlands of boreal and alpine parts of the northern hemisphere that has a slender subterraneous rhizome and delicate solitary triangular fronds

Word History

Etymology

translation of Latin dryopteris

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

• More than 250,000 words that aren't in our free dictionary
• Expanded definitions, etymologies, and usage notes
• Advanced search features
• Ad free!