Al-marfūʿ (literally, that which is raised) is what is attributed to the Messenger of Allāh ﷺ.1
Muqaddimat Ibn al-Ṣalāḥ, pp. 42–44. Taqrīr (the Prophet's tacit approval) falls under the first heading because it counts as a statement in juristic terms, or under the second because the act of remaining silent is itself an action, as Shaykh Muḥammad Salmān al-Sahāranpūrī cites in Taqrīr al-Mishkāt (p. 3) on the authority of al-Awjaz. Note, however, that the tacit approval of someone other than the Prophet ﷺ is not necessarily attributed to him unless it is free of any cause that would prevent objection, in contrast to the Prophet's own tacit approval. ↩
Al-mawqūf (literally, halted) consists of the sayings and actions of the Companions, may Allāh be pleased with them.
If any one of the attributes of the ṣaḥīḥ or the ḥasan is missing, the ḥadīth is ḍaʿīf (literally, weak).
Al-maqṭūʿ (literally, severed) consists of the sayings and actions of the tābiʿūn and those after them.
Al-mursal al-khafī is a mursal whose omission is concealed; clarity and concealment are relative, varying with the rank of the critic.
