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