I9, i9 or I-9 may refer to: Science and technology Intel Core i9, a line of high performance processors of the Skylake-X and Kaby Lake-X range Gulftown, microprocessors originally rumored to be called the Intel Core i9 Straight-nine engine, a straight engine with nine cylinders, usually diesel engines used for ship propulsion ICD-9, a coding system for medical diagnoses and procedures Other uses Form I-9, a U.S. Citizenship and Immigration Services form Interstate 9, a proposed upgrade to California State Route 99 Skaraborg Regiment (infantry), a Swedish Army infantry regiment disbanded in 1942 , an Imperial Japanese Navy submarine See also I Nine, an American band