IPA: /ˈmoʊtərˌsaɪklɪst/
KK: /ˈmoʊtərˌsaɪklɪst/
A person who rides a motorcycle.
The motorcyclist wore a helmet for safety.
Motorcyclist → It is formed from "motor" (from Latin "movere", meaning to move) and "cycle" (from Greek "kyklos", meaning circle or wheel) and "-ist" (meaning one who practices or is concerned with). The word "motorcyclist" refers to one who rides a motorcycle, which is a vehicle that moves on wheels.
Think of someone who is concerned with a vehicle that moves ('motor') on wheels ('cycle') — that's what a motorcyclist does.