thank

Etymology 1

From Middle English thank, from Old English þanc (“thought, favour, grace, pleasure, satisfaction, thanks”), from Proto-Germanic *þankaz (“thought, remembrance, gratitude”), from Proto-Indo-European *tong-, *teng- (“to think”). Cognate with Saterland Frisian Tonk, West Frisian tank, Dutch dank, Low German Dank, German Dank, Danish tak, Swedish tack, Faroese tøkk, Icelandic þökk. Related to thought.

noun

1. (obsolete in the singular) An expression of appreciation; a thought.

Etymology 2

From Middle English thanken, thankien, from Old English þancian, þoncian (“to thank, give thanks”), from Proto-Germanic *þankōną (“to thank”), from Proto-Germanic *þankaz (“thought, gratitude”), from Proto-Indo-European *teng- (“to think, feel”). Cognate with Saterland Frisian tonkje (“to thank”), West Frisian tanke (“to thank”), Dutch danken (“to thank”), Low German danken (“to thank”), German danken (“to thank”), Danish takke (“to thank”), Swedish tacka (“to thank”), Icelandic þakka (“to thank”). Of the same root as the above etymology. Related to thought.

verb

1. (transitive) To express gratitude or appreciation toward.
   She thanked him for the lift.
   I told him about everything I could think of; and what I couldn't think of he did. He asked about six questions during my yarn, but every question had a point to it. At the end he bowed and thanked me once more. As a thanker he was main-truck high; I never see anybody so polite. 1913, Joseph C. Lincoln, chapter 4, in Mr. Pratt's Patients
2. (transitive) To feel gratitude or appreciation toward.
   I'll thank you not to smoke in my house!
   Our readers would not thank us for going into the badgerings which had for some time annoyed the chancellor on the subject of arrears in his court. 1844, The Quarterly Review, volume 74, page 104
3. (transitive) To credit or hold responsible.
   We can thank global warming for this weather.