Halal: permitted, allowed, lawful, legal. The acts or things which are permitted and lawful. There is neither reward for performing it nor any punishment for neglecting it. For example: drinking tea.
Haram: forbidden, prohibited. lt is necessary to abstain from the acts which are haram. If someone performs a haram act, then he or she will be punished either by the Islamic court or in the hereafter or both. For example: stealing.
Jaiz: same as halal. See above.
Makruh: reprehensible, disliked, and discouraged. Acts which are disliked but not haram. If someone docs a makruh act, then he or she will not be punished for it; however, if people refrain from it, then they will be rewarded. For example: eating with left hand.
Mubah: same as halal, except that the term “mubah” is exclusively used for lawful things and properties, not for acts.
Mujtahid: a jurist. The term is used to describe a Shi'a Muslim religious scholar who is an expert of' Islamic jurisprudence (fiqh). Commonly it is used for the high ranking mujtahids whose decrees are followed by the Shi'a people. Such mujtahids arc also known as “marja'” or "Ayatullah''.
Mustahab: recommended, desirable, better. It refers to the acts which are recommended but not wajib. If one neglects them, then he or she will not be punished; however, if one performs them, then he or she will be rewarded. For example: washing hands before eating.
Shari'ah or Shari'a: literally means a way, a stream: in Islamic terminology, it means the laws of Islam.
Sunnat: same as Mustahab. See above.
Wajib: obligatory, necessary, incumbent. An act which must be performed. A person will be rewarded for performing it and punished for neglecting it. For example: the daily prayers.