as a noun, 'muster' refers to an assembly or gathering, especially of troops for inspection or for a specific purpose. It can also refer to a group or collection of people or things.
The soldiers were preparing for the morning muster.
There was a large muster of supporters at the rally.
The muster of birds in the sky was a magnificent sight.
The term 'roll call' is sometimes used interchangeably with 'muster' in contexts where individuals are being accounted for. 'Muster' as a noun can also refer to the act of mustering, i.e., the process of gathering or assembling.
when 'muster' is used as a verb, it primarily refers to the action of assembling (troops), especially for inspection or in preparation for battle. Additionally, it can mean to gather or summon up a feeling or response.
The general mustered his troops for a final briefing before the battle.
She tried to muster the courage to confront her boss about the issue.
I couldn't muster enough enthusiasm for the event.
'muster' in the context of gathering feelings or responses is often followed by a noun that represents the emotion or response being summoned.
The phrase 'muster up' can be used interchangeably with 'muster' in many contexts.