Contrary to bitter_engineer's posting, the size of a
word depends on the
architecture. Although to x86 programmers it normally means "16 bits" (due to various
crap we won't get into right now), strictly-speaking a word is the
native data
size. Most modern CPUs have a 32-bit-sized word.
That said, assume that any given bit pattern can produce one (and only one) picture. Well, then the number of pictures which a word is worth is 2 to the power of the number of bits in the word - that is, a 32-bit word can represent 232 unique images - so for most systems, a word is worth 4294967296 pictures!
Of course, assuming a bitmap with no compression, that picture will only be a 32-pixel monochrome image, but the single word can be much more expressive than that - for example, it could the a seed value for a pseudorandom number generator used by a random artwork simulator, so although any particular word has no specific meaning for the image, any two unique words will generate vastly different images.