http://php.net/manual/pt_BR/reserved.keywords.php
Here they are as arrays:
$keywords = array('__halt_compiler', 'abstract', 'and', 'array', 'as', 'break', 'callable', 'case', 'catch', 'class','clone', 'const', 'continue', 'declare',
'default', 'die', 'do', 'echo', 'else', 'elseif', 'empty', 'enddeclare','endfor', 'endforeach', 'endif', 'endswitch', 'endwhile', 'eval', 'exit',
'extends', 'final', 'for', 'foreach','function', 'global', 'goto', 'if', 'implements', 'include', 'include_once', 'instanceof', 'insteadof',
'interface','isset', 'list', 'namespace', 'new', 'or', 'print', 'private', 'protected', 'public', 'require', 'require_once','return', 'static',
'switch', 'throw', 'trait', 'try', 'unset', 'use', 'var', 'while', 'xor');
$predefined_constants = array('__CLASS__', '__DIR__', '__FILE__', '__FUNCTION__', '__LINE__', '__METHOD__','__NAMESPACE__', '__TRAIT__');?>