adverb
quite a lot; a good deal; plenty
Colloquial adverb indicating a large amount, often with a nuance of satisfaction or excess. Used mainly in casual speech.
お年玉をたんまりもらった。
I got quite a lot of New Year's money.
彼はたんまり稼いでいるらしい。
He seems to be earning a good deal.
The origin is uncertain. It may be a sound-symbolic word (mimetic) emphasizing abundance, but the exact derivation is unclear.