wallah; walla
noun
1
a man identified by relation to the activity, occupation or philosophy to which it is properly affixed. Adopted directly by Anglo-Indians, hence military, from Hindu wálá ('a person connected in some way with the thing expressed in the first word', George Clifford Whitworth, An Anglo-Indian Dictionary, 1885) INDIA, 1785.
2
in the television and film industries, indistinguishable background voices US, 1990