Definition of "non-euclidean" []

• Not comprehended within or not in conformity with the system of geometry established by Euclid; pertaining to or designating any system of geometry which, while differing in essential particulars from that of Euclid, is nevertheless in accord with the facts of experience within the limits of the errors of observation.

The Century Dictionary (Public Domain)

• "At the same time I was just getting into reading stories by HP Lovecraft, all that barely-restrained hysteria and cosmic horror, mind-cracking abominations bubbling up from beneath the floorboards of non-euclidean, rat-infested cellars, or leering from the dark, unbalanced vistas painted by former inmates of some creaking Providence institution whose walls are stained with the shrieks of vanished patients…."
• "I have to figure out how to fit "non-euclidean" in there someplace and I've got an H.P. Lovecraft story on my hands."
• "February 14, 2010 at 9:51 am a weird packing foam structure that comes in the box for the new laptop you ordered from Best Buy, but which appears on closer inspection to be designed to fit and cushion not an ordinary laptop, but an unknowable item of non-euclidean dimensions."