Noah Webster
Prism
PRISM, noun [Low Latin prisma; Gr. to cut with a saw, to press or strain.] A solid whose bases or ends are any similar, equal and parallel plane figures, and whose sides are parallelograms.
A prism of glass is one bounded by two equal and parallel triangular ends and three plain and well polished sides which meet in three parallel lines, running from the three angles of one end to the three angles of the other end.