extremely; exceedingly; deeply
Used with verbs and adjectives to express a high degree; often found in literary or formal contexts.
彼の言葉にいたく感動した。
I was deeply moved by his words.
Only when written 痛く
Rare adverbial use of 痛い, meaning 'in a painful manner'; mostly seen in older or literary texts.
傷が痛くて眠れなかった。
The wound hurt so much I couldn't sleep.
I was deeply moved by that story.
その知らせを聞いて、いたく驚いた。
I was extremely surprised to hear the news.
I deeply sympathized with his misfortune.
He seemed to have taken a great liking to that painting.
He deeply regrets his own words and actions.
ひどく often carries a negative or excessive nuance ('terribly'), whereas 痛く is more neutral in tone despite its formality.
非常に is a common formal intensifier used in speech and writing, while 痛く is rarer and has an old-fashioned, literary flavor.
甚だ is another literary intensifier close in register to 痛く, both meaning 'exceedingly' but sounding stiff in modern speech.
Usually written in kana; the kanji forms 痛く and 甚く are rare and may be confused with other readings.
Rare kanji form for the 'painfully' sense; easily confused with the common adjective 痛い.
Rare kanji form for the 'extremely' sense; not in common use.
Adverbial form of the adjective いたい (痛い, 'painful'), with the sense 'extremely' developing from the idea of something being so intense it hurts.