tree fern

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various tropical treelike ferns having a woody trunklike stem and a terminal crown of large, pinnately divided fronds.

Century Dictionary and Cyclopedia

1. n. One of several species of ferns that attain to the size of trees. They belong mostly to the tribe Cyatheæ, and are confined to the tropics, where they form a striking feature of the landscape, sending up a straight trunk to a height of 25 feet or more, crowned at the summit with a cluster of large drooping fronds. Several species are successfully cultivated in greenhouses. See Cyathea and fern.

Wiktionary

1. n. Any of many tropical plants, of the families Cyatheaceae and Dicksoniaceae, that have tall trunks topped with fronds.

GNU Webster's 1913

1. n. (Bot.) an arborescent fern having a straight trunk, sometimes twenty or twenty-five feet high, or even higher, and bearing a cluster of fronds at the top. Most of the existing species are tropical.

WordNet 3.0

1. n. any of numerous usually tropical ferns having a thick woody stem or caudex and a crown of large fronds; found especially in Australia and New Zealand; chiefly of the families Cyatheaceae and Marattiaceae but some from Polypodiaceae