say'
n. uncountable C1 Advanced Oxford US //ˈseɪ// UK //sˈeɪ// say
n. the power or right to decide something. You use this when you want to show that someone has a part in making a final choice.
n. the opportunity or right to express an opinion or influence a decision. Often used in the singular and frequently follows the verb 'to have'.
Usage
Typically used in the singular form with the indefinite article ('a say'). Often paired with the prepositions 'in' or 'over'.
Pitfall
I want to have a say about the projectI want to have a say in the projectWhile 'about' is sometimes heard, 'in' is the standard preposition used when referring to participating in a decision.