noun

• (by extension, derogatory) A person or animal regarded as resembling a scarecrow (sense 1) in some way; especially, a tall, thin, awkward person; or a person wearing ragged and tattered clothes.
  "The ſeely man ſeeing him ryde ſo ranck, / And ayme at him, fell flatt to ground for feare, / And crying Mercy loud, his pitious handes gan reare. // Thereat the Scarcrovv vvexed vvondrous provvd, / Through fortune of his firſt aduenture fayre, / And vvith big thundring voice reuyld him lovvd; […]"
• (dated) Synonym of crow scarer (“a farmhand employed to scare birds from the fields”).
• (figuratively)
  "VVith ſcoffes and ſcornes, and contumelious taunts, In open Market-place produc't they me, To be a publique ſpectacle to all: Here, ſayd they, is the Terror of the French, The Scar-Crovv that affrights our Children ſo."
• (figuratively)

verb

• (archaic) To spoil the appearance of (something, such as the landscape or a view), as scarecrows may be regarded as doing.
  "Fatigued and hungry as our party were after a long drive through the desolate region of malaria, wild buffaloes, wild birds, and yet wilder specimens of the human race, which here and there scare-crow the broad, sadly picturesque expanse between the last cork-trees near Salerno, and the treeless vicinage of the temple of Neptune, we dared not venture upon fish with green bones,—the only dish served up for our repast; […] we all preferred bearing our hunger, and traversing a second time the fiery plain unrefreshed, to breaking our fast upon such suspicious diet; […]"