在preg_replace中排除一个单词

Question

I have a code which replaces some characters using preg_replace:

$pattern=array(
        "#Y#",//full year
        "#y#",//short year

        "#M#",//month short name
        "#F#",//month full name
        "#m#",//month number 0 lead
        "#n#",//month number
        "#t#",//days in month

        "#l#",//full week day
        "#D#",//short week day

        "#d#",//day number of month
        "#j#",//day number of month

        "#a#",//AM/PM short view
        "#A#",//AM/PM full view

        "#H#",
        "#i#",
        "#j#",
        "#n#",
        "#O#",
        "#P#",
        "#s#",
        "#w#",
                );
    $replace=array(
        $d->ENnum2FA($converted[0]),//year 13xx
        $d->ENnum2FA(substr($converted[0],2),true),//year xx lead zero

        $d->shmonths[$converted[1]],//month name
        $d->months[$converted[1]],//month name
        $d->ENnum2FA($converted[1],true), //month number
        $d->ENnum2FA($converted[1]), //month number
        //$converted[1],
        $d->j_days_in_month[$converted[1]],

        $d->days[strtolower(gmdate("D",$stamp))],//week day {full view}
        $d->ldays[strtolower(gmdate("D",$stamp))],//week day ‍‍{short view}

        $d->ENnum2FA($converted[2],true),//day of month
        $d->ENnum2FA($converted[2],true),//day of month

        $d->pmam[gmdate('a',$stamp)],
        $d->pmam[gmdate('A',$stamp)],

        $d->ENnum2FA(gmdate('H',$stamp)),
        $d->ENnum2FA(gmdate('i',$stamp)),
        $d->ENnum2FA(gmdate('j',$stamp)),
        $d->ENnum2FA(gmdate('n',$stamp)),
        $d->ENnum2FA(gmdate('O',$stamp)),
        $d->ENnum2FA(gmdate('P',$stamp)),
        $d->ENnum2FA(gmdate('s',$stamp)),
        $d->ENnum2FA(gmdate('w',$stamp)),
        );

        $date= preg_replace($pattern,$replace,$format);

Now, I want it to replace all those characters in every string except the word "relative". As you can see, the characters "a", "i" , "r" are in the word I want it to remain unchanged. How can I do this?