Rupa, Sanskrit, “form,” in Buddhism rupa is associated with nama as in rupa-nama, in the analysis of human appearance to denote corporeality.
The general definition of rupa in Eastern religions is the means through which the accidental and transitory flux of appearance achieves identifiable shape. By means on rupa, appearance becomes an object of perception. But the term applies especially in Hinduism to the representation of gods, which are then contrasted with lesser objects of perception, stones, trees, etc.; the latter have form, nevertheless, they are called arupa--literally “formless”; but clearly something “aniconic,” not bearing a divine form. A.G.H.
Bowker, John, The Oxford Dictionary of World Religions, New York, Oxford University Press, 1997, p. 826