An Etymological Dictionary of the German Language/Annotated/täglich
täglich, adjective and adverb ‘daily,’ from the equivalent Middle High German tagelîch (tegelîch), adjective, tagelichen (tege-lîches), adverb, Old High German tagalîh, adjective, tagalîhhin, tagolîhhes, adverb. The adjective has been formed from the adverb, which is again a combination of two words, as in the phrase (allaro) tago gilîh (hes); for gilîh in the sense of ‘every,’ see männiglich; tago gilîhhes (literally ‘on each of the days’) is an adverb genit. like Old High German, Middle High German, and Modern High German des tages. See further verteidigen.