Source: The Collaborative International Dictionary of English v.0.48
Euclidian \Eu*clid"i*an\, n.
Related to Euclid, or to the geometry of Euclid.
[1913 Webster]
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 flatspace, and homaloidal space.
[1913 Webster]