I heard the words "topic" for $_ and "topicalizer" for any function setting $_ go around, since in linguistic sense $_ is the topic of your conversation with the parser.

In perl6 this concept will be more elaborate.

#<perl6>
my $str = "some string\n";
given $str {
    chomp;
    print $_." is now our topic\n";
}
#</perl6>
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--
Jaap Karssenberg || Pardus (Larus)? <pardus@cpan.org>
>>>> Zoidberg: So many memories, so many strange fluids gushing out of patients' bodies.... <<<<