also: とっくのむかし
Dated expression meaning 'a long time ago'; the modern equivalent is とっくの昔. Often used in narrative or nostalgic contexts.
See also: とっくの昔
That's a story that ended a long time ago.
A festival handed down from long ago still continues today.
Kanji form using 疾く; less common and may be unfamiliar to modern readers.
More common modern variant with geminated とっく. Included as a practical search variant.
From とく (an old adverbial form meaning 'quickly' or 'long ago') + の + 昔 (ancient times). The exact derivation of とく is uncertain, but it is related to the classical adverb 疾く.