"a collection of tools, utensils, etc. adapted as a means to some end," 1620s, from Latin apparatus "tools, implements, equipment; preparation, a preparing," noun of state from past participle stem of apparare "prepare," from ad "to" (see ad-) + parare "make ready" (from PIE root *pere- (1) "to produce, procure").
1550s, "faint sketch, imperfect representation," from Latin adumbrationem (nominative adumbratio) "a sketch in shadow, sketch, outline," noun of action from past-participle stem of adumbrare "to cast a shadow, overshadow," in painting, "represent (a thing) in outline," from ad- "to" (see ad-) + umbrare "to cast in shadow," from PIE root *andho- "blind; dark" (see umbrage).
Latin, literally "A Step to Parnassus," the mountain sacred to Apollo and the Muses; from Latin gradus "a step; a step climbed; a step toward something" (from PIE root *ghredh- "to walk, go"). Also see Parnassus. It was the title of a dictionary of prosody used in English public schools for centuries as a guide to Roman poetry. The book dates from the 1680s. Also the name of a treatise on musical composition written in Latin by Johann Joseph Fux, published in Vienna in 1725, and of a much-used book of exercises for piano.