IPA: /ˈstæɡərər/
KK: /ˈstæɡərər/
A person or thing that moves unsteadily or with difficulty, often due to being drunk or injured.
The staggerer struggled to keep his balance as he walked down the street.
Staggerer is formed from "stagger" (from Old English *stacgan*, meaning to sway or totter) and "-er" (meaning a person who). A staggerer is a person who sways or totters, often unsteadily.
Think of someone who 'sways' ('stagger') and the '-er' just means a person. A staggerer is someone who sways or moves unsteadily.