Source: Webster's Revised Unabridged Dictionary (1913)

Festoon \Fes*toon"\, n. [F. feston (cf. Sp. feston, It.
festone), prob. fr. L. festum festival. See Feast.]
1. A garland or wreath hanging in a depending curve, used in
decoration for festivals, etc.; anything arranged in this
way.

2. (Arch. & Sculp.) A carved ornament consisting of flowers,
and leaves, intermixed or twisted together, wound with a
ribbon, and hanging or depending in a natural curve. See
Illust. of Bucranium.
Festoon \Fes*toon"\, v. t. [imp. & p. p. Festooned; p. pr. &
vb. n. Festooning.]
To form in festoons, or to adorn with festoons.

Long time ago I was briefly interested in the various names for various types of garlands--we've seen here mention of various forms of wreaths, laurels, crowns. And the festoon is quite distinct in its shape and purpose.

But what is it called that hangs straight down from a balcony for festive occasions? A huge banner that usually has lettering and decoration on it?

There was a young lady named Rhoda
Who dwelt in a Chines Pagoda
The walls and the halls
were festoonedwith the baxxx
And the txxxx of the fools
Who bestrode her. (The ones who best rode her went free)