/keuh lis"tin/ , n. Pharm.
a toxic antibiotic polypeptide, C 45 H 85 O 10 N 13 , produced by the bacterium Bacillus colistinus, used in sulfate form against a broad spectrum of microorganisms and in the treatment of severe gastroenteritis.
[ 1950-55; colistinus epithet for a variety of Bacillus polymyxa, equiv. to coli- (see COLIFORM) + -stinus, appar. an arbitrarily chosen suffix; cf. -IN 2 ]