http://php.net/manual/en/reserved.keywords.php
__halt_compiler() | abstract | and | array() | as |
break | callable (as of PHP 5.4) | case | catch | class |
clone | const | continue | declare | default |
die() | do | echo | else | elseif |
empty() | enddeclare | endfor | endforeach | endif |
endswitch | endwhile | eval() | exit() | extends |
final | finally (as of PHP 5.5) | for | foreach | function |
global | goto (as of PHP 5.3) | if | implements | include |
include_once | instanceof | insteadof(as of PHP 5.4) | interface | isset() |
list() | namespace(as of PHP 5.3) | new | or | |
private | protected | public | require | require_once |
return | static | switch | throw | trait (as of PHP 5.4) |
try | unset() | use | var | while |
xor | yield (as of PHP 5.5) |
__CLASS__ | __DIR__(as of PHP 5.3) | __FILE__ | __FUNCTION__ | __LINE__ | __METHOD__ |
__NAMESPACE__(as of PHP 5.3) | __TRAIT__(as of PHP 5.4) |