Chapter Dowgate Ward to Dragon of D by Brewer's Phrase & Fable

the meaning a watcher we get the notion of one that watches; and from the meaning "to flash," we connect the word with meteors.

"Swift, swift, ye dragons of the night: - that dawning
May bare the raven's eye."
Shakespeare: Cymbeline, ii. 2.

   Dragon. This word is used by ecclesiastics of the Middle Ages as the symbol of sin in general and paganism in particular. The metaphor is derived from Rev. xii. 9, where Satan is termed "the great dragon." In Ps. xci. 13 it is said that the saints "shall trample the dragon under their feet." In the story of the Fall, Satan appeared to Eve in the semblance of a serpent, and the promise was made that in the fulness of time the seed of the woman should bruise the serpent's head.
   Another source of dragon legends is the Celtic use of the word for "a chief." Hence pen-dragon (summus rex), a sort of dictator, created in times of danger. Those knights who slew a chief in battle slew a dragon, and the military title soon got confounded with the fabulous monster. Dragon, meaning "quicksighted," is a very suitable word for a general.
   Some great inundations have also been termed serpents or dragons. Hence Apollo (the sun) is said to have destroyed the serpent Python (i.e. dried up the overflow). Similarly, St. Romanus delivered the city of Rouen from a dragon, named Gargouille (waterspout), which lived in the river Seine.
   From the idea of watching, we have a dragon placed in the garden of the Hesperides; and a duenna is poetically called a dragon:

"In England the garden of beauty is kept
By a dragon of prudery placed within call;
But so oft the unamiable dragon hath slept,
That the garden's but carelessly watched after all."
T. Moore: Irish Melodies, No. 2 ("We may roam
through this world," etc.).

    A spiteful, violent, tyrannical woman is called a dragoness.
   The blind dragon, the third party who plays propriety in flirtations.

"This state of affairs was hailed with undisguised thankfulness by the rector, whose feeling for harmony had been rudely jarred by the necessity of his acting the blind dragon" - J. O.Hobbes: Some Emotions and a Moral, chap. iv.

   Dragon in Christian art symbolises Satan or sin. In the pictures of St. Michael and St. Margaret it typifies their conquest over sin. Similarly, when represented at the feet of Christ and the Virgin Mary. The conquest of St. George and St. Silvester over a dragon means their triumph over paganism. In the pictures of St. Martha it means the inundation of the Rhone, spreading pestilence and death; similarly, St. Romanus delivered Rouen from the inundation of the Seine, and Apollo's conquest of the python means the same thing. St. John the Evangelist is sometimes represented holding a chalice, from which a winged dragon is issuing.
   Ladies guarded by dragons. The walls of feudal castles ran winding round the building, and the ladies were kept in the securest part. As adventurers had to scale the walls to gain access to the ladies, the authors of romance said they overcame the serpent-like defence, or the dragon that guarded them. Sometimes there were two walls, and then the bold invader overcame two dragons in his attempt to liberate the captive damsel. (See Enchanted Castles.)
   A flying dragon. A meteor.
   The Chinese dragon. In China, the drawing of a five-clawed dragon is not only introduced into pictures, but is also embroidered on state dresses and royal robes. This representation is regarded as an amulet.
   The Green Dragon. A public-house sign in compliment to St. George.
   The Red Dragon. A public-house sign in compliment to Henry VII., who adopted this device for his standard at Bosworth Field. It was the ensign of Cadwallader, the last of the British kings, from whom the Tudors descended.