blank check

1 ENTRIES FOUND:
blank check (US) noun
or British blank cheque
plural blank checks
blank check (US)
noun
or British blank cheque
plural blank checks
Britannica Dictionary definition of BLANK CHECK
[count]
1 
: a signed check that does not have the amount of money written on it yet
2 
informal : complete control or freedom — often used in the phrase give/hand (someone) a blank check