Definition from Wiktionary, the free dictionary
Alternative forms 
From Middle English hercnen, from Old English *heorcnian, suffixed form of an assumed *heorcian (cf. hark), from the same root as hȳran (whence hear), with a formative/intensive -k. Equivalent to hark + -en.
- (intransitive) To listen; to lend the ear; to attend or give heed to what is uttered; to hear with attention, obedience, or compliance.
- The Furies hearken, and their snakes uncurl.
- Bible, Deuteronomy
- Hearken, O Israel, unto the statutes and unto the judgments, which I teach you.
- (transitive, poetic) To hear by listening.
- (transitive) To hear with attention; to regard.
- (obsolete) To enquire; to seek information.
- Hearken after their offense.
- 1611, King James Version of the Bible (Authorized Version), Genesis 3:17
- And unto Adam he said, Because thou hast hearkened unto the voice of thy wife, and hast eaten of the tree, of which I commanded thee, saying, Thou shalt not eat of it: cursed is the ground for thy sake; in sorrow shalt thou eat of it all the days of thy life;
- 1833: Alfred Tennyson, Œnone
- Dear mother Ida, harken ere I die.
- 1809-49: The Tell-Tale Heart, Edgar Allan Poe
- How then am I mad? Hearken! and observe how healthily, how calmly, I can tell you the whole story.
- hearken in The Century Dictionary, The Century Co., New York, 1911