IPA: /ˈkwiːziər/
KK: /ˈkwizɪər/
Feeling slightly sick or uncomfortable, especially in the stomach; this form indicates a greater degree of that feeling compared to the base form.
After the roller coaster ride, I felt queasier than before.
Queasier → It is formed from "queasy" (from Middle English *queis*, meaning uneasy or nauseated) and the comparative suffix "-er" (meaning more). The word "queasier" means more uneasy or more likely to feel nauseated than something else.
Think of feeling 'uneasy' or 'nauseated' when you are 'more' so than usual — that's what queasier means.