The Collaborative International Dictionary of English v.0.48:
Cycloidal \Cy*cloid"al\ (-al), a. Pertaining to, or resembling, a cycloid; as, the cycloidal space is the space contained between a cycloid and its base. [1913 Webster] Cycloidal engine. See Geometric lathe. [1913 Webster]WordNet (r) 3.0 (2006):
cycloidal adj 1: resembling a circle [syn: cycloid, cycloidal]