An Etymological Dictionary of the German Language/täglich
täglich, adj. and adv. ‘daily,’ from the equiv. MidHG. tagelîch (tegelîch), adj., tagelichen (tege-lîches), adv., OHG. tagalîh, adj., tagalîhhin, tagolîhhes, adv. The adj. has been formed from the adv., 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 (lit. ‘on each of the days’) is an adverb genit. like OHG., MidHG., and ModHG. des tages. See further verteidigen.