carefully; thoroughly; deliberately
Used when someone does something with full attention, without rushing, or after careful consideration. Often appears in the set phrase とくとご覧あれ (take a good look).
This problem needs to be thought through carefully.
Behold! / Take a good look!
Rare kanji spelling; the kana form is strongly preferred in modern usage.
The origin is uncertain. The kanji 篤 means 'sincere' or 'earnest', which fits the adverbial meaning, but the word is now treated as a lexicalized adverb usually written in kana.