A speed freak is someone who obsessively seeks out the adrenaline rush of high-speed activities. This term is often associated with drug use, but not always. If you're looking for different ways to describe this type of person without using the term "speed freak," there are plenty of options. A few possible synonyms include thrill-seeker, daredevil, high-speed enthusiast, adrenaline junkie, and speedster. Other phrases that may capture the same idea include velocity addict, pace-obsessed, or speed-demon. While each of these terms carries slightly different connotations, all of them evoke the idea of someone who craves the excitement and danger of moving at high speeds.