grouser

/ˈɡraʊsər/
noun
  1. A person who complains or grumbles frequently.
    • He's known as a grouser who finds fault with everything.
    • Don't be such a grouser; the food is fine.
    • The manager had to deal with a grouser who complained about the new policy.
Antonyms
What does "grouser" mean? | whatsthatwordmean | whatsthatwordmean