Erst has 3 different meanings across 1 category:
Adverb
Adjective
Adverb
1
at a previous time
"at one time he loved her"
"her erstwhile writing"
"she was a dancer once"
2
First of all, before (some other specified thing).
Example Sentences
"at one time he loved her"
adverb
"her erstwhile writing"
adverb
"she was a dancer once"
adverb