Definition of "flaps"

Giges or flappes, is pimples or teates in the in side of his mouth.

1587, Leonard Mascall, The First Booke of Cattell, London: John Wolfe, page 163

If there be any ſwelling betweene the eares, it is a ſigne of the Pole-evil: ſwelling under the eare, a ſigne of the Vives; and ſwelling in the mouth, a ſigne either of Canker, Flaps, Lampaſſe.

1610, Gervase Markham, “Of the signes of sicknesse, and of what nature it consisteth”, in Markhams Maister-peece. Contayning All Knowledge Belonging to the Smith, Farrier, or Horse-leech, Touching the Curing of All Diseases in Horses: ), page 32

Theſe Giggs, Bladders or Flaps, proceed either from eating too much Graſs, or that which is bad; or Hay or Provender that is rough and pricking.

1726, N. B. Philippos, The Farrier's and Horseman's Dictionary, London: J. Darby, page 247

The Flaps are a ſpungy, fleſhy, fungous ſubftance, ſituated juſt below the grinders on the lower jaw, adjoining the cheek, on the part where the bit reſteth upon. The above is ſo troubleſome to a Horſe and ſo ſore, that he will often catch the Flaps between his grinders, which chafes him much, and prevents him to grind his food, and cauſes him to ſlaver and ſlober much.

1784, William Griffiths, A Practical Treatise on Farriery, Wrexham, Wales: R. Marsh, page 119

These likewise sometimes enlarge during catarrh or imflammation of the mouth, and are called gigs, and bladders, and flaps in the mouth.

1843, William Youatt, The Horse, London: Chapman & Hall, page 206