Try something similar for just one request, although I don’t know how effective such a request will be:
$possibilities = array( "at", "ta");
$sql = 'SELECT * FROM dictionary_table
WHERE word IN ("' . implode( '", "', $possibilities) . '")';
This will generate an SQL query:
SELECT * FROM dictionary_table
WHERE word IN ("at", "ta")
, , , $possibilities , . word.