IPA: /ˈveɪkəntli/
KK: /ˈveɪkəntli/
In a way that shows a lack of thought or attention; without any expression or interest.
She stared vacantly at the wall, lost in her thoughts.
Vacantly → It is formed from "vacant" (from Latin "vacans", meaning empty or unoccupied) and the suffix "-ly" (meaning in a manner of). The word "vacantly" means in a manner that is empty or unoccupied, often referring to a lack of thought or attention.
Think of 'vacant' meaning empty, and remember that 'vacantly' describes doing something in an empty or unoccupied manner, like when someone seems lost in thought.