Japanese

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For pronunciation and definitions of つきつめる – see the following entry.
突き詰める
[verb] to investigate thoroughly; to examine closely; to probe into; to get to the bottom of the truth of the matter
[verb] to brood over, to be obsessed over a thought
Alternative spellings
突きつめる, 突詰める
(This term, つきつめる, is the hiragana spelling of the above term.)