What does "for good" mean?

for a long time without essential change

What is a synonym for "for good"?

Common synonyms include: aye, ever, ever and again, ever and anon, evermore, finally.

/fə ˈɡʊd/ prep_phrase

prep_phrase ·Rare ·Advanced level

Adverb

Prep_phrase

1
In a way that is conclusive and final. idiomatic
"A bad haircut is no fun, but at least you’re not stuck with it for good, only until it grows out."

"A bad haircut is no fun, but at least you’re not stuck with it for good, only until it grows out."

From for (“over (a period of time)”, preposition) + good (“of an action: complete, thorough, utter”, adjective).