formal parameter

formal parameter :

[3.16] object declared as part of a function declaration or definition that acquires a value on
entry to the function,

Example :

int x (int y, int z);

int b (int zz, int cc) {
return zz + cc ;
}

y and z and zz and cc are both formal parameters.

Reference :

C11 ISO_IEC 9899
n1570