Ziyadat al-thiqah: A compatible addition by a reliable narrator is accepted in principle; a truly incompatible addition requires preference according to the evidence.
Mahfuz and shadh: An accepted narrator's outweighed conflicting account is shadh, and the stronger corresponding account mahfuz.
Ma`ruf and munkar: A weak narrator's contradictory inferior account is munkar, and its stronger counterpart ma`ruf.
Two questions remain distinct throughout: How trustworthy is this narrator in general? and Which particular version is best preserved? The first does not automatically answer the second.
Collecting further routes may reveal that an apparently solitary transmission has a corroborating account. The terms mutaba`ah, shahid, and i`tibar describe aspects of that inquiry and form the next lesson.