[ad. Gr. κυκλοειδής, κυκλώδης circular: see CYCLE and -OID.] Resembling a circle; spec. in Zool. a. Of a somewhat circular form, with concentric striations; applied to the scales of certain fishes. b. Belonging to the Cycloidei, or order of fishes with cycloid scales.
1847. Ansted, Anc. World, iv. 62. The remaining two groups [of Fishes] are called respectively Ctenoid … and Cycloid … from the shape and structure of the scale.
1851. Richardson, Geol. (1855), 283. Nearly all the cycloid genera … are extinct.
1872. H. A. Nicholson, Palæont., 326. Scales cycloid or rhomboid.
