babbitter
bæbɪtər (noun: /ˈbæbɪtər/, verb: /ˈbæbɪtər/)
Definitions
1. noun
A person who habitually or excessively complains or speaks negatively.
“The babbitter of the group always found something to complain about.”
2. verb
To talk excessively or habitually in a negative or complaining manner.
“She was babbittering about the service at the restaurant all night.”