Photobacterium \Pho`to*bac*te"ri*um\ (f[=o]`t[-o]*b[a^]k*t[=e]"r[-e]*[u^]m), n. [NL. See {Photo-}, and {Bacterium}.] (Bacteriol.) A genus including certain comma-shaped marine bacteria which emit bluish or greenish phosphorescence. Also, any microorganism of this group. [Webster 1913 Suppl.]