Procrusteus was an inn-keeper who (according to the story) always made sure his guests fitted the beds exactly, either by cutting off their feet or by stretching them on a rack. So if a system is "procrustean", it means it always makes sure things fit -- if necessary by taking very drastic action.
For example, some programming languages might use "procrusteun string assignment". Suppose I am using a programming language that makes sure all strings are exactly eight characters in length. It might use procrustean assignment: if the string is too short -- "rewboss", for example, has only seven characters -- then it adds spaces to make the string long enough; if the string is too short, it just chops the end off, so "usingenglish" would become "usingeng".