Fuddy-duddy

Fuddy-duddy is an idiom that seems to have been coined in the United States. An idiom is a commonly used word, group of words, or phrase that has a figurative meaning that is not easily deduced from its literal definition. Often using descriptive imagery or metaphors, common idioms are words and phrases used in the English […]
from Grammarist
https://grammarist.com/idiom/fuddy-duddy/