$ perl -e 'use JSON; use Data::Dump; my $x = do { local $/; <> }; dd(decode_json $x)' pm_1201279_input.json
{
  def  => [
            {
              pos  => "noun",
              text => "time",
              tr   => [
                        {
                          gen  => "m",
                          mean => [{ text => "day" }, { text => "moment" }],
                          pos  => "noun",
                          syn  => [
                                    { gen => "f", pos => "noun", text => "volta" },
                                    { gen => "m", pos => "noun", text => "momento" },
                                    { gen => "m", pos => "noun", text => "Time" },
                                  ],
                          text => "tempo",
                        },
                      ],
              ts   => "ta&#618;m",
            },
          ],
  head => {},
}

##</code><code>##

$ perl -e 'use JSON; use Data::Dumper; my $x = do { local $/; <> }; print Dumper decode_json($x)' pm_1201279_input.json
$VAR1 = {
          'def' => [
                     {
                       'text' => 'time',
                       'tr' => [
                                 {
                                   'syn' => [
                                              {
                                                'pos' => 'noun',
                                                'text' => 'volta',
                                                'gen' => 'f'
                                              },
                                              {
                                                'pos' => 'noun',
                                                'text' => 'momento',
                                                'gen' => 'm'
                                              },
                                              {
                                                'pos' => 'noun',
                                                'text' => 'Time',
                                                'gen' => 'm'
                                              }
                                            ],
                                   'text' => 'tempo',
                                   'gen' => 'm',
                                   'pos' => 'noun',
                                   'mean' => [
                                               {
                                                 'text' => 'day'
                                               },
                                               {
                                                 'text' => 'moment'
                                               }
                                             ]
                                 }
                               ],
                       'pos' => 'noun',
                       'ts' => 'ta&#618;m'
                     }
                   ],
          'head' => {}
        };

##</code><code>##

$ perl -E 'use JSON; my $j = do { local $/; <> }; my $p = decode_json $j; say $p->{def}' pm_1201279_input.json
ARRAY(0x7f8e1c881968)

##</code><code>##

$ perl -E 'use JSON; my $j = do { local $/; <> }; my $p = decode_json $j; say $p->{def}[0]' pm_1201279_input.json
HASH(0x7f89ee002e30)

##</code><code>##

$ perl -E 'use JSON; my $j = do { local $/; <> }; my $p = decode_json $j; say for keys $p->{def}[0]->%*' pm_1201279_input.json
ts
pos
tr
text