Towards, forward, anterior.
[Greek pros, towards; prosō, forwards.]
This appears in a few words imported from Greek, such as proselyte (Greek erkhesthai, come); prosody (Greek ōidē, song); and prosthesis (Greek prosthesis, addition, from tithenai, to place), originally the addition of a letter or syllable at the beginning of a word, but now also an artificial body part. A few scientific terms contain it, mostly dating from the nineteenth century: prosencephalon (Greek enkephalos, brain), another word for the forebrain; prosenchyma (Greek enkhuma, infusion), a plant tissue consisting of elongated cells with interpenetrating tapering ends; prosobranch (Greek brankhia, gills), a member of a group of molluscs which includes the limpets and abalones. It is not an active word forming element.