Euclidian \Eu*clid"i*an\, n. Related to Euclid, or to the geometry of Euclid.

Euclidian space (Geom.), the kind of space to which the axioms and definitions of Euclid, relative to straight lines and parallel lines, apply; -- called also flat space, and homaloidal space.

Source: Webster's Revised Unabridged Dictionary (1913)