unwrittenun‧writ‧ten /ʌnˈrɪtn/ adjective 
Examples
unwritten rules of social behaviour
ExamplesEXAMPLES FROM THE CORPUS
Thesaurus- Both sides claimed the other had broken a 1993 unwritten agreement to avoid targeting civilians.
- By an unwritten rule, they avoided controversy for the sake of good fellowship.
- Norms can be thought of as unwritten rules.
- One of the unwritten job descriptions of a basketball coach is as second father to the players.
- Whatever the outcome the long-standing, unwritten code of behaviour that governs relations between ministers and civil servants would be gravely battered.
- Without unwritten rules civilised life would be impossible.
Longman Language Activatorrules of acceptable behaviour► convention
Collocations the rules and customs of acceptable behaviour, which are generally accepted by the members of a group or society: · He is a flamboyant millionaire who ignores social conventions.convention of: · She shocked her neighbours by ignoring every convention of respectable society.a matter of convention: · It is a matter of convention that male business people usually wear suits.defy convention (=do something unconventional): · For the next four years they defied convention by living as man and wife when they were not.
► protocol the system of rules for behaviour on official occasions: · According to protocol, he was to arrive at the meeting exactly five minutes early.breach of protocol (=behaviour not according to protocol): · Touching the Queen was a breach of royal protocol.
► etiquette the rules of polite behaviour in society or in a particular group: · Etiquette is especially important on occasions such as weddings and funerals.breach of etiquette (=behaviour not according to etiquette): · It was considered a breach of etiquette to refuse an invitation.professional etiquette (=the etiquette followed by people working in a particular profession): · Professional etiquette dictates that judges should not express their opinions about a case in public.
► unwritten law a rule or way of behaving that is not official but is accepted by most members of a society or group: · It was an unwritten law of the Mafia that nobody should talk to the police.· Jobs like this never go to women -- it just seems to be one of those unwritten laws of business.
► netiquette informal the commonly accepted rules for polite behaviour when you are communicating with other people on the Internet: · Sending an angry e-mail in capital letters breaks the rules of netiquette.
COLLOCATIONS FROM OTHER ENTRIES► an unwritten constitution
Word family (=a constitution that is not formally written down as a separate document)· Britain's unwritten constitution allows for flexibility when circumstances change.
► an unwritten rule (=a rule of behaviour that everyone in a group understands)· There’s an unwritten rule that you never call an actor before 10 a.m.
COLLOCATIONS FROM THE CORPUSNOUN► rule· Certain unwritten rules may apply with regard to hospitality.· Although people management is not a science, it has a system of unwritten rules and logic.· Norms can be thought of as unwritten rules.· By an unwritten rule, they avoided controversy for the sake of good fellowship.· Without unwritten rules civilised life would be impossible.· But managers know the unwritten rules when they enter the business.· There are a number of unwritten rules or axioms which perhaps need to be questioned.· There is an unwritten rule in their crowd.
WORD FAMILYnounwriterwritingrewriteverbwriterewriteadjectivewritten ≠ unwritten
an unwritten rule, law, agreement etc is one that everyone knows about although it is not official: unwritten rules of social behaviour