(Science: zoology) One of several species and varieties of large arctic falcons, especially. Falco rusticolus and the white species f. Islandicus, both of which are circumpolar. The black and the gray are varieties of the former.
alternative forms: gerfalcon, gierfalcon, and jerfalcon.
Origin: oe. Gerfaucon, OF. Gerfaucon, LL. Gyrofalco, perh. Fr. L. Gyrus circle – falco falcon, and named from its circling flight; or cf. E. Gier-eagle. See Gyre, falcon.