1 definition found central islip - U.S. Gazetteer (1990) : Central Islip, NY (CDP, FIPS 13552) Location: 40.78542 N, 73.19693 W Population (1990): 26028 (7697 housing units) Area: 15.2 sq km (land), 0.0 sq km (water) Zip code(s): 11722