adj

• (botany) With the sides meeting directly to form an acute angle (at an apex or base).
  "204. Eremophila abietina […] Corolla 23–35 mm long, cream or very pale lilac, lobes faintly metallic bluish green or lilac, tube occasionally brownish, prominently purple spotted; outer and inner surfaces glandular-pubescent; lobes acute, lobe of lower lip strongly reflexed."
• (geometry, of an angle) Less than 90 degrees.
  "The teacher pointed out the acute angle."
• (geometry, of a triangle) Having all three interior angles measuring less than 90 degrees.
  "an acute triangle"
• (linguistics, chiefly historical) Of an accent or tone: generally higher than others.
  "Let this [the word alalal] be ſpoken as an Engliſh word, with the ſtrong accent on either ſyllable, or, on each, in repeating the word; and, no change of articulation diſturbing the ear, it will be abundantly evident that, with ordinary Engliſh pronunciation, the strengthened syllable has always the acuter tone, or, in muſical phraſe, the higher note."

noun

• (medicine, informal) A person who has the acute form of a disorder, such as schizophrenia.
  "Anne Marie had been assigned a ‘constant supervision’ status. […] Always avoiding the unrest of the television lounge, she would sometimes join some of the older ‘acutes’ who sat isolated in metal chairs at the end of the hallway and gaze out of the window with them."
• (linguistics, chiefly historical) An accent or tone higher than others.
  "[I]t would be strange if we wer to recite Homer, raising our voices on the acutes, lowering them on the graves, and managing the circumflexes as well as we could, yet to recite Virgil without any of these regular elevations, depressions, and circumbendibus."
• (orthography) An acute accent (´).
  "The word ‘cafe’ often has an acute over the ‘e’."

verb

• (transitive, phonetics) To give an acute sound to.
  "He acutes his rising inflection too much."
• (transitive, archaic) To make acute; to sharpen, to whet.
  "[A]n old Farmer […] uſed, when fuddled over Night, to walk naked, or only in his Shirt, until he had cooled himſelf throughly, […] This Courſe may not be improperly call'd a Balenum Aerium, and may be of great Uſe to ſober People, as well as the Fuddlers; for running empty, after Sleep and Concoction, warms the Blood and Spirits, acutes the Circulations, fans and cools the Lungs, helps both Excretion and Secretion; […]"