Jisho

×
Adverb (fukushi), Adverb taking the 'to' particle
1. deeply; keenly; severely; completely; utterly​Usually written using kana alone, Onomatopoeic or mimetic word
Adverb (fukushi), Adverb taking the 'to' particle
2. intently; carefully; closely; attentively​Usually written using kana alone, Onomatopoeic or mimetic word
Other forms
熟 【つくつく】、熟熟 【つくづく】、熟熟 【つくつく】、熟々 【つくづく】、熟々 【つくつく】
Notes
熟: Rarely-used kanji form. 熟: Rarely-used kanji form. 熟熟: Rarely-used kanji form. 熟熟: Rarely-used kanji form. 熟々: Rarely-used kanji form. 熟々: Rarely-used kanji form.

Discussions

to talk about this word.