Acts that are punishable in the hereafter, and rewardable to avoid:
- Prohibited (Haraam) refers to an act that is sinful and punishable in the hereafter. It is known by obvious proofs from the Quran, Hadith or Scholarly Consensus. Examples include adultery, fornication and drinking wine. The worst kind of prohibited act is called blasphemy, which are sayings, beliefs and doings that make one a non-Muslim.
- Prohibitively Disliked (Makruuh taHriimii) refers to an act that is sinful and punishable in the hereafter, but it is not known by obvious proofs. An example would be shaking hands with someone of the opposite sex and a desirable age who is not a relation, even if it is without desire. Another example is sitting alone in a room with such a person.
- Haraam (prohibited) & Makruuh (disliked) are sometimes used as synonyms.
Acts that are NOT punishable in the hereafter, but rewardable to avoid:
- Virtuously Disliked (Makruuh tanziihhii) refers to a disliked act that is neither sinful nor punishable in the hereafter, but it is rewardable to leave it for the sake of Allah.
- The word “Makruuh” / “disliked” alone might mean prohibitively or virtuously.
Mandatory acts that are punishable to leave out:
- Obligation (Fard) refers to an act that is known to be punishable to leave by obvious proofs. Obligatory acts include the 5 daily prayers and fasting in Ramadan.
- Duty (Waajib) refers to an act that is known to be punishable to leave by proofs that are not obvious. An example is the Eid prayer for men.
- Fard “Obligation” and Waajib “Duty” are often used as synonyms.
Optional rewardable acts:
- Ascertained Merit (Sunnah Muakkadah) refers to an optional act that the Prophet persistently did for the purpose of worship, but left out a few times. To leave it out is blameworthy, but not punishable in the hereafter.
- Virtue or Etiquette (MustaHabb or Adab) refers to an optional act that the Prophet did a few times for the purpose of worship. Some say that the former is of somewhat higher rank.
- Merit, Virtue and etiquette are often used as synonyms.
Acts in terms of their fulfillment of prerequisites or conditions:
- Valid (Sahiih) refers to an act that has had all its prerequisites and conditions fulfilled, such as a valid prayer.
- Invalid (baaTil) refers to an act that did not have all its prerequisites or conditions fulfilled, such as an invalid prayer.
Acts that are allowed:
- Permitted (mubaaH) refers to acts that are allowed, such as eating bread.
- Sometimes the word Jaa'iz in Arabic refers to something mubaaH, other times it means "valid." Beware that something "valid" may still have a sin in it, such as selling grapes to someone who wants to make wine from them. That is, the transaction is valid in that ownership was transferred, but the seller commited a sin.