pro ‧ vi ‧ so /prəˈvaɪzəʊ $ -zoʊ/ BrE AmE noun ( plural provisos ) [countable] formal
[ Date: 1400-1500 ; Language: Medieval Latin ; Origin: proviso quod 'provided that' ]
a condition that you ask for before you will agree to something
with the proviso that
The money was given to the museum with the proviso that it is spent on operating costs.