Definition from Wiktionary, the free dictionary
allegedly (not comparable)
- According to someone's allegation.
- The suspect was allegedly involved in the robbery, but his alibi placed him in another state at the time.
- According to someone's conspicuous impressions (which could be alleged ensuingly).
- The game is allegedly exciting.
Usage notes 
- This term is used in the media to avoid litigation when the facts are not 100% certain, or when referring to evidence in an ongoing trial.
according to someone's allegation