Adverb
Usually written in kana
1. very; extremely; surprisingly; fairly; quite; considerably; awfully; terribly
でも、随分無理もしてたんだろう。But, I guess they must have been pushing themselves pretty hard.
Adjective (な)
Usually written in kana
2. terrible; horrid; contemptible; reprehensible
ずいぶんな挨拶だな。What a rude greeting.
3. remarkable; extraordinary