Weakness arising from the loss of uprightness and precision:
Among its subdivisions:
• al-mukhtaliṭ (the confused): a transmitter whose memory deteriorated because of old age, loss of eyesight, or the disappearance of his notebooks. Whatever he related before the confusion is accepted, while anything that cannot be distinguished is left in suspense.
• al-munkar (denounced): a report narrated by a weak transmitter that conflicts with what a reliable transmitter narrates; its opposite is called al-maʿrūf (recognized).
• al-mubham (anonymous): where the transmitter is unknown.
• al-matrūk (abandoned): a report conveyed by someone known among people for lying.
• al-mawḍūʿ (fabricated): a report related by a narrator proven to have deliberately lied about the Messenger of Allah (peace and blessings be upon him).
Weakness stemming from a break in the chain of transmission:
• al-maqṭūʿ (severed): a statement or action ascribed to a Successor or anyone below him, whether the chain is continuous or broken.
• al-munqaṭiʿ (broken): where one or more transmitters—non-consecutively—are missing before the Companion.
• al-muʿḍal (perplexingly broken): where two or more consecutive transmitters are missing at any point in the chain.
• al-muʿallaq (suspended): where one or more transmitters are omitted from the beginning of the chain.
• al-mursal (hurled forward): a report in which a Successor narrates directly from the Prophet (peace and blessings be upon him).
• al-mudallas (obfuscated), which has two forms:
- Tadlīs al-isnād (chain obfuscation): when the narrator gives the impression that he heard directly from his teacher although he did not, employing an ambiguous wording.
- Tadlīs al-shuyūkh (teacher obfuscation): when the narrator transmits from a teacher but identifies him with a name by which he is not known, so that he remains unidentified.
Weakness due to irregularity or a hidden defect:
• al-shādh (anomalous): a report narrated by an acceptable transmitter that contradicts what is narrated by someone more reliable; its counterpart is called al-maḥfūẓ (preserved).