1 definition found waialua - U.S. Gazetteer (1990) : Waialua, HI (CDP, FIPS 74000) Location: 21.57760 N, 158.12852 W Population (1990): 3943 (1205 housing units) Area: 3.2 sq km (land), 0.5 sq km (water) Zip code(s): 96791