However, in a small number of words, a vowel affected by i-umlaut is not marked with the umlaut diacritic because its origin is not obvious. Either there is no unumlauted equivalent or they are not recognized as a pair because the meanings have drifted apart. The adjective "fertig" ("ready, finished"; originally "ready to go") contains an umlaut mutation, but it is spelled with "e" rather than "ä" as its relationship to "Fahrt" ("journey") has, for most speakers of the language, been lost from sight. Likewise, "alt" ("old") has the comparative "älter" ("older"), but the noun from this is spelled "Eltern" ("parents"). "Aufwand" ("effort") has the verb "aufwenden" ("to spend, to dedicate") and the adjective "aufwendig" ("requiring effort") though the 1996 spelling reform now permits the alternative spelling "aufwändig" (but not * "aufwänden"). For "denken", see below.