IPA: /rɪˈhɜːrsər/
KK: /rɪˈhɜrsər/
A person who practices a performance, such as a play or music, in order to prepare for a public presentation.
The rehearser spent hours perfecting their lines before the opening night.
Rehearser → It is formed from "re-" (meaning again) and "hear" (from Old English "herian", meaning to hear or listen) and the suffix "-er" (meaning a person who). The word "rehearser" refers to a person who hears or listens again, typically in the context of rehearsing a performance or practice.
Think of someone who listens 'again' ('re-') to something ('hear') — that's why a rehearser is a person who goes over something again.