1. An arthropod of the order Araneida (subclass Arachnida) characterized by four pairs of legs; a cephalothorax; a globose, smooth abdomen; and a complex of web-spinning spinnerets. Among the venomous spiders found in the New World are the black widow s., Latrodectus mactans; red-legged widow s., Latrodectus bishopi; pruning s., or Peruvian tarantula, Glyptocranium gasteracanthoides; Chilean brown s., Loxosceles laeta; Peruvian brown s., Loxosceles rufiper; brown recluse s. of North America, Loxosceles reclusus. 2. An obstructive growth in the teat of a cow. [O. E. spinnan, to spin]
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spi·der 'spīd-ər n
1) any of an order (Araneae syn. Araneida) of arachnids having a body with two main divisions, four pairs of walking legs, and two or more pairs of abdominal spinnerets for spinning threads of silk used esp. in making webs for catching prey
2) SPIDER NEVUS <an arterial \spider>
3) an obstruction in the teat of a cow esp a small irregular horny growth resulting from irritation or bruising
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spi·der (spiґdər) 1. any arachnid of the order Araneae, usually characterized by a body in two parts: the cephalothorax, which has eight legs attached, and the abdomen. Some species have venomous bites. Cf. arachnidism. 2. spider angioma.Medical dictionary. 2011.