a person who is extremely interested and knowledgeable about computers, electronics, technology, and gadgets; also called nerd , geek
derogatory slang
the part of a motor that converts basic motor speed to rated output speed and increases motor torque
A devotee of cars, car racing, etc: translating that into monosyllables for you gearheads/ Robin Yount has always been a gearhead (1970s+)