$ perl -E 'say ((defined $x) ? "defined" : "undef")' 
undef
$ perl -E 'say ((defined defined $x) ? "defined" : "undef")'
defined
$ perl -E '$x = 1; say ((defined $x) ? "defined" : "undef")'
defined
$ perl -E '$x = 1; say ((defined defined $x) ? "defined" : "undef")'
defined