Dewlap

n. fold of skin which hangs under the throat of certain animals (i.e. cows)

A dewlap is a flap of skin that hangs beneath the lower jaw of tetrapods, that is, amphibians, reptiles, birds, mammals and their relatives. While the term is usually used in this specific acception, it can also be used to include other structures occurring in the same body area with a similar aspect, such as those caused by a double chin or the sub-mandibular vocal sac of a frog. In a more general manner, the term refers to any pendulous mass of skin, such as a fold of loose skin on an elderly person's neck, or the wattle of a bird. There are also dewlaps on dogs such as the English Springer Spaniel, the Basset Hound or the Mastiff. The dewlap is also common on certain breeds of rabbit, such as the New Zealand white rabbit. Although these masses can be referred to as dewlaps, they are formed by stored fat.
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Dewlap loose skin under the throat and neck which may be pendulous in some species or breeds, e.g. Bloodhounds, Indian cattle, rabbits. [more]Dewlap - Community and Resources

Noun
1. a hanging fold of loose skin on an elderly person's neck
(hypernym) skin, tegument, cutis
(part-holonym) neck, cervix

(n.)
The pendulous skin under the neck of an ox, which laps or licks the dew in grazing.
  

(n.)
The flesh upon the human throat, especially when with age.