al ‧ lege /əˈledʒ/ BrE AmE verb [transitive often passive] formal
[ Date: 1300-1400 ; Language: Old French ; Origin: alleguer , from Latin allegare 'to give reasons' , from ad- 'to' + legare ( ⇨ ↑ legate ) ]
to say that something is true or that someone has done something wrong, although it has not been proved
it is alleged (that)
It was alleged that the policeman had accepted bribes.
allege that
The prosecution alleged that the man had been responsible for an act of terrorism.
be alleged to be/do something
The water is alleged to be polluted with mercury.