Entries related to dotty
"point or minute spot on a surface," Old English dott, once, "speck, head of a boil," perhaps related to Norwegian dot "lump, small knot," Dutch dot "knot, small bunch, wisp," Old High German tutta "nipple;" a word of uncertain etymology.
Known from a single source c. 1000; the word reappeared with modern meaning "mark" c. 1530; not common until 18c. Perhaps this is a different word imitative of "the mark of a mere touch with the pen" (Wedgwood). In music, the meaning "point indicating a note is to be lengthened by half" is by 1806. Morse telegraph sense is from 1838. On the dot "punctual" is 1909, in reference to a clock dial face. Dot-matrix in printing and screen display is attested by 1975.
c. 1200, doten, "behave irrationally, do foolish things, be or become silly or deranged," also "be feeble-minded from age," probably from an unrecorded Old English word akin to Middle Low German and Middle Dutch doten "be foolish, be out of one's mind," all of which are of unknown origin, or directly from these words.
Century Dictionary and OED compare Dutch dutten "take a nap; mope;" Icelandic dotta "to nod, sleep;" Middle High German totzen "take a nap." Wedgwood writes, "The radical sense seems to be to nod the head, thence to become sleepy, to doze, to become confused in the understanding."
From late 15c. as "be infatuated, bestow excessive love." Also in Middle English "to decay, deteriorate," in reference to rotten timber, etc. (mid-15c.). There was a noun dote "fool, simpleton, senile man" (mid-12c.), but Middle English Compendium considers this to be from the verb. Related: Doted; dotes; doting.