for good
idiom

- permanently, forever

(American Heritage Dictionary)

---
The adjective "good" can be used in a variety of ways to mean different things.

In combination with the preposition "for" as in "for good," it means permanently. Here are some good suggestions for other uses:

- as good as = practically, nearly (The car looked as good as new.)

- but good = used to note the intensity of something (Bill injured his knee but good while skiing)

- good and = very, thoroughly (I'll finish the report when I'm good and ready)

- no good = worthless, useless (It's no good washing the car now because it's going to rain soon)

- to the good = for the best, in an advantageous position (When I left the casino I was to the good)

---
SMUGGLE OWAD into today's conversation

"Since Tom is leaving London for good, we should give him a farewell party."