imaginary
From cppreference.com
                    
                                        
                    
                    
                                                            
                    | Defined in header  <complex.h> | ||
| #define imaginary _Imaginary | (since C99) | |
This macro expands to a type specifier used to identify imaginary complex types. The macro is defined only if the implementation supports imaginary types.
| This section is incomplete Reason: on what condition? The standard seems unclear. Maybe when __STDC_IEC_559_COMPLEX__ is defined? | 
A program may undefine and perhaps then redefine the imaginary macro.
[edit] See also
| (C99) | complex type macro (macro constant) | 


