'rock brake' definitions:
Definition of 'rock brake'
(from WordNet)
noun
Any of several small lithophytic ferns of tropical and warm temperate regions [syn: cliff brake, cliff-brake, rock brake]
noun
Dwarf deciduous lithophytic ferns
noun
Chiefly lithophytic or epiphytic fern of North America and east Asia [syn: rock polypody, rock brake, American wall fern, Polypodium virgianum]