HSK C7-9
Correct

颓

/ tuí / 
Strokes

Definition

to crumble/to collapse/to decline/to decay/decadent/dejected/dispirited/balding

Example

As a Verb
collapse; topple down; become ruined/dilapidated
As a Verb
decline; decay
As an Adjective
decadent; dejected; dispirited