Mutawātir متواتر — continuous multiple sources of transmission
Some reports were passed down by so many people and so many different sources that they are considered undeniable. These narrations are preserved as reliably as the Qurʾān itself. These Aḥādīth are called Mutawātir.
This is as opposed to reports that scholars call Mash′hūr مشهور (passed down by a very small number of reporters to an eventually very large number) and . The latter category is also called Khabar al-Wāhid.
Āḥād ءاحاد — single report
single reports passed down by a small number of people to a small number
Ṣaḥīḥ صحيح — authentic
When analyzing these single reports, scholars have developed different methods to determine which ones can be considered accurate and reliable (Ṣaḥīḥ).