An Etymological Dictionary of Astronomy and Astrophysics

1. Chem.: Composed of only one → substance or → element.
   

2. Math.: Consisting of, involving, or describable by → terms of the → first degree.
   

3. Music: Uncompounded or without overtones.

Etymology (EN): M.E., from O.Fr. simple, from L. simplus “simple, single,” variant of simplex, from PIE root *sem- “one, together;” cf. Pers. ham “together,” → com-, Skt. sam “together;” + *plac- “-fold,” from PIE *plek- “to plait,” → multiply.

Etymology (PE): Sâdé “simple, unmixed, smooth, erased, plain;” cf. Khotanese sāta- “smooth;”
Baluchi sāt/sāy-, sāh- “to shave;” Av. si-, sā- “to sharpen, cut;” Skt. śā- “to sharpen, whet” (Cheung 2007); see also → precise.