unwritten

Word family  noun writer writing rewrite adjective written ≠ unwritten verb write rewrite

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++un·writ·ten /ʌnˈrɪtn/ adjective  RULE/REGULATIONan unwritten rule, law, agreement etc is one that everyone knows about although it is not official 〔规则、法律、协议等〕非书面的，不成文的 unwritten rules of social behaviour 不成文的社会行为规范

Examples from the Corpus

unwritten• Both sides claimed the other had broken a 1993 unwritten agreement to avoid targeting civilians.• Whatever the outcome the long-standing, unwritten code of behaviour that governs relations between ministers and civil servants would be gravely battered.• One of the unwritten job descriptions of a basketball coach is as second father to the players.• By an unwritten rule, they avoided controversy for the sake of good fellowship.• Without unwritten rules civilised life would be impossible.• Norms can be thought of as unwritten rules.

un·writ·ten adjectiveChineseSyllable  

is that law, unwritten agreement etc one an rule, Corpus

unwritten
un‧writ‧ten /ʌnˈrɪtn/ adjectivean unwritten rule, law, agreement etc is one that everyone knows about although it is not official:
    unwritten rules of social behaviour

un·writ·tenBrE /ˌʌnˈrɪtn/ 🔊NAmE /ˌʌnˈrɪtn/ 🔊 adjective~ law, rule, agreement, etc. a law, etc. that everyone knows about and accepts even though it has not been made official 非书面的，不成文的，惯常的（法律、规定、协议等）◆an unwritten understanding that nobody leaves before five o'clock五点钟之前谁都不离开的默契(of a book, etc. 书等) not yet written 未写的；未写完的◆The photographs were to be included in his as yet unwritten autobiography. 这些照片准备要收入他那尚未写的自传之中。🔊🔊