/si"treuh leen'/ , n. Biochem.
an amino acid, NH 2 CONH(CH 2 ) 3 CHNH 2 COOH, abundant in watermelons and an intermediate compound in the urea cycle.
[ 1930; citrull ( us ) the watermelon genus (ML citrul ( l ) us, citrolus, Latinization of South It citrulo, Tuscan citri ( u ) olo citrium watermelon (deriv. of L citrus (see CITRUS); appar. in reference to the citroncolored fruit of some types of watermelon), with -uolo -eolus ) + -INE 2 ]