Meaning

verb make smooth or smoother, as if by rubbing

verb make (a surface) shine

verb become smooth

originUltimately the same as etymology 1. The gene encoding the protein was first identified in Drosophila melanogaster as a segment polarity gene and initially named smooth (smo) by Christiane Nüsslein-Volhard et al. in 1984. This was later revised to smoothened by Dan L. Lindsley and Georgianna G. Zimm in 1992, because the former name already described another locus.

Etymology from Wiktionary, CC BY-SA 3.0