Queterract is a 4th-dimensional sphere. "Kwetwer-" is the Indo-European
root for "four" and "act" coming from the latin root "ἀκτίς" (aktis) meaning "ray".
Just like a
tesseract is comprised of "tessera-", meaning "four"
as well, and "ἀκτίς" (aktis), a queterract is comprised of what's stated above.