All 5 Uses of

flourish

in

Macbeth

SCENE IV. Forres. A Room in the Palace.
[Flourish. Enter Duncan, Malcolm, Donalbain, Lennox, and Attendants.]
p. 25.8 *

flourish = fanfare played by trumpets to announce the entry or exit of royalty

[Flourish. Exeunt.] (at end of Act 1 Scene 4)
p. 29.9

flourish = wave or make a showy gesture

Flourish. Enter, with drum and colours, Malcolm, old Siward, Ross, Lennox, Angus, Caithness, Menteith, and Soldiers.
p. 187.7

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.