An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) Notably sharp, clear-cut, and clear.
2) Noticeably neat (Merriam-Webster.com).

M.E, from O.E., from L. crispus "curled," cognate with Walsh crych "curly."

Tuj (Kurmanji Kurd.) variant of tiz, → sharp.

A classical set that allows only full membership or no membership at all for its elements, as contrasted with a → fuzzy set. Crisp set can be viewed as a restricted case of the more general fuzzy set concept.