CA3, CA-3, or Ca.3 may refer to: Carbonic anhydrase III, muscle specific, a human gene Cornu Ammonis region 3, one of the hippocampal subfields United States Court of Appeals for the Third Circuit Buhl-Verville CA-3 Airster Buhl CA-3 Airsedan CAC CA-3 Wirraway California's 3rd congressional district California State Route 3 Caproni Ca.3, an Italian heavy bomber of World War I and the post-war era