Both Uses

flourish
in
Kit's Wilderness
(Edited)

Great place for young life to flourish.
p. 6.3 *

flourish = grow or develop well
He swung his arm out with a flourish.
p. 29.7 *

flourish = a showy gesture

Definitions:

(1) (flourish as in: the business is flourishing)
to thrive (grow or develop well)
(2) (flourish as in: dismissed them with a flourish)
a showy gesture

or:

the act of waving -- a hand or an item
(3) (meaning too rare to warrant focus)
In Shakespeare's plays, flourish is often used as a stage direction indicating a specific type of showy gesture: fanfare played by trumpets or other horns to announce the entry or exit of royalty.

Check a comprehensive dictionary for other senses including some that are of interest to musicians.