Bazm means gathering or party, an assembly of people. Also known as mehfil.
Here is a couplet from the prolific collection of Ghalib’s poetry:
उस बज़्म में मुझे नहीं बनती हया किये
बैठा रहा अगरचे इशारे हुआ किये
I cannot be shy or bashful in that gathering
Where I sit with (alluring) gestures being made (directed towards me)