The way car people talk can confuse an outsider. Some of the terms are straightforward words for parts or racing terms, while others are a sort of slang that reflects car culture.
Aftermarket Refers to parts intended for installation on a car after it is purchased from the dealership, usually designed to differ from the parts on the car when it left the factory. As a noun, the market for such parts, and the companies that supply them.
AN fittings Originally developed for the military (AN means Army-Navy), this standard of fitting is often used on race cars. Most AN fittings work with braided hoses.
Anti-roll bar A flexible bar that ties the left and right sides of the suspension together to reduce body roll.
Autocross A racing ...