6 LETTER WORD: G T R E E S

6 LETTER WORD
GREETS

5 LETTER WORD
EGRETS
TREES
TERSE
STEER
SERGE
RESET
GREET
ESTER
EGRET

4 LETTER WORDS
TREE
TEEs
SERE
SEER
REST
GETS
GEES
ERST
ERGS

3 LETTER WORDS
TEE
SET
SEE
GET
GEE
ERG
ERE

What's erst mean?
Archaic .
before the present time; formerly.

I've heard of erstwhile, but never just erst on its own!

More than that, I guess I'd never looked up the definition of erstwhile. I had always assumed, from context, that it meant, "good friends", not "former friends." Ya learn something new every day.