unwritten
adj
ʌnˈrɪtn
adj
1
an
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