Chillicothe (chi-li-KA-thee), city (1990 pop. 5,959), Peoria co., central Ill., on Illinois R., at N end of L. Peoria, and 15 mi/24 km NNE of Peoria; 40°55'N 89°30'W. In agr. and bituminous-coal area; sand, gravel pits; mfg. (clothing, concrete prods.). Inc. 1861.