What is suffix for kindly?

There is no common suffix for "kindly". "Kindly" is already an adverb, meaning "in a kind manner" or "with kindness".

If you're looking for a way to make the word more intense or formal, you might consider:

* Adding "very" or "extremely" in front: "very kindly," "extremely kindly"

* Using synonyms like "graciously", "generously", "considerately": These words have similar meanings and might suit the context better.

For example, instead of "He kindly offered his seat," you could say:

* "He very kindly offered his seat"

* "He graciously offered his seat"

* "He generously offered his seat"