(picture definition of the "word" zazen)The nature of a word's meaning has been an Achilles Heel, stumbling linguistics for hundreds of years. For example, Pāṇini's 4th Century Sanskrit grammar Astadhyayi (Aṣṭādhyāyī - अष्टाध्यायी) appears to have accepted that "the authority of the popular usage of words … must supersede the authority of the meaning dependent on derivation. The meanings of words (the relations between word and meaning) are also established by popular usage" (more here).
The Urban Dictionary is a great example of this kind of approach to dictionary making and now The Photographic Dictionary is trying to use pictures to define words (HT: Daily Dish). It's an interesting project, linguistically as well as artistically. I doubt these pics have been normed for their "meaning" (to be fair, it's more of an art project than linguistic research), but it's a good move towards functional definitions of words. I'd prefer to see multiple pictures (and videos??) for each word that have been normed to some extent for the meanings they are supposed to represent. For example, when I looked at the picture definition for the "word" zazen (above), a word I had never seen before, I did not feel that one picture helped me understand the meaning of the word. If anything, it confused me because I could imagine any number of conflicting meanings associated with that one pitcures. No one meaning was salient. This is classic function/structuralist linguistics. Cognitive semantics grew out of exactly this kind of problem.
And, for the record, my answer to the question in this post's title is this: I have no idea. See Princeton's Construction Site for more on my confusion.