Illustrated Companion to the Latin Dictionary/Groma

This article incorporates text from a publication now in the public domain: Rich, Anthony (1849). The illustrated companion to the Latin dictionary, and Greek lexicon. p. vi. OCLC 894670115. https://archive.org/details/illustratedcompa00rich. 

GROMA and GRUMA (γρώμων). An instrument used by land-surveyors, engineers, and persons of that class; which was set up as an index for the purpose of enabling them to draw their lines, or direct their roads perfectly straight to any given point. (Non. s. v. p. 63. Hyg. de Limit. p. 164. Goes.) Hence degrumari, to make straight (Lucil. Sat. iii. 15. Gerlach.); and grumae, the central point at which four cross-roads meet. Non. l. c.