Syenite \Sy"e*nite\, n. [L. Syenites (sc. lapis), from Syene, Gr. ?.]

(Min.)
   (a) Orig., a rock composed of quartz, hornblende, and feldspar, anciently quarried at Syene, in Upper Egypt, and now called granite.
   (b) A granular, crystalline, ingeous rock composed of orthoclase and hornblende, the latter often replaced or accompanied by pyroxene or mica. Syenite sometimes contains nephelite (el[ae]olite) or leucite, and is then called nephelite (el[ae]olite) syenite or leucite syenite.

Source: Webster's Revised Unabridged Dictionary (1913)