Noun
Unfaithfulness
in
a
marriage
or
an
intimate
(
sexual
or
romantic
)
relationship
:
practice
or
instance
of
having
a
sexual
or
romantic
affair
with
someone
other
than
one
'
s
spouse
,
without
the
consent
--think
of
polyamorous
relationships--
>
of
the
spouse
.