<?php 

$re = '/(?|(c)(hapters?))\s*((\d+(?:\.\d+)?(?:[A-Z]\b)?)(?:\s*(?:[,&+-]|and)\s*(?:\b(?:c(?:hapters?))\s*)?(?4))*)/ui';
$str = 'chapter 2.5 2 cái địt mẹ mày';

preg_match($re, $str, $matches);

// Print the entire match result
echo $matches[0];