if (/$_[0] =~ /^([^:]+):([^|]+)(?:\|(.*))?$/ ||
     $_[0] =~ /^([^|)+)\|(.*)$/) {
    @key{qw /name definition altdefinition/} = ($1, $2, defined $3 ? $3 : "")
}

##</code><code>##

if ($_[0] =~ /\|/) {
  @key{qw /name definition altdefinition/} = split /\|/, $_[0];
  $key{altdefinition} = "" unless defined $key{altdefinition};
}