stick-in-the-mud /ˈstɪkənðəˌmʌd/ noun plural stick-in-the-muds
plural stick-in-the-muds
Learner's definition of STICK-IN-THE-MUD
[count] informal + disapproving
: someone who has old-fashioned ideas or who does not like trying new or exciting things守旧的人;墨守成规的人