Helen, I thought this had been mentioned before here, so I did a Search; look how apropos Dr. Bill's post was:
From a dictionary of mathematical terms:
"Ahe word parallelogram, according to its etymology, signifies parallel lines; it no more
suits the figure of four sides than it does that of six, of eight, &c. which have their opposite
sides parallel. In like manner, the word parallelopipedon signifies parallel planes; it no more
designates the solid with six faces, than the solid with eight, ten, &c. of which the opposite
faces are parallel. The names parallelogram and parallelelopipedon*, have the additional
inconvenience of being very long. Perhaps, therefore, it would be advantageous to banish them
altogether from geometry; and to substitute in their stead, the names rhombus and rhomboid,
retaining the term lozenge, for quadrilaterals whose sides are all equal.

http://wordsmith.org/board/showthreaded.pl?Cat=&Board=words&Number=79849