"Worship." To display one's ultimate servitude and helplessness in front of someone. This is a general term applied to religious observances such as prayer, fasting, hajj, payment of poor due, etc. Additionally, this term has very wide application in the Islamic sense-- it includes not only ritual acts of worship such as the salah but any action done by a human being for the pleasure of and in obedience to the Almighty Allah. Thus, eating, drinking, and interacting with other creatures and human beings with the proper intention and according to the sunnah can count as ibadah and one will be rewarded for it.

"Knowledge," or a "science," as in 'ilm-ul-fiqh (the science of jurisprudence) or 'uloom-ul-Qur'an (the sciences of the Qur'an).

"Leader." (1) A person who leads the congregational salah. (2) The great scholars of Islamic jurisprudence or hadith are also often given this title.

In the Shi'ah doctrine, however, the term covers an entirely different notion. To them the Imam is the faultless and infallible leader, an offspring of 'Ali , to whom spiritual leadership is supposed to have been passed on from the Prophet Muhammad through his son-in-law and the fourth khaleef, i.e. 'Ali .