IPA: /ˈweɪkər/
KK: /ˈweɪkər/
A person or thing that causes someone or something to wake up.
The waker gently shook her friend to help her get out of bed.
Waker → The word is formed from "wake" (from Old English *wacan*, meaning to become awake or to arise) and "-er" (meaning a person who). A waker is a person who wakes or causes someone to wake.
Think of someone who helps others 'arise' or 'become awake' — that's what a waker does.