RASUL means Messenger. It is distinguishable from a nabi in that a RASOOL is bestowed with a holy book from Allah.‎

Moreover, the title of ‘rasul’ applies more directly to Muhammad [PBUH] and generally to those prophets who were sent with divine Books. In the Kalimah‐e‐Shahada (first cardinal article of faith) the Muhammad [PBUH]’s name is accompanied with this title’ but in the kalima of any other RASOOL, this is not the case. A rasool is one who brings Allah’s Message to His servants.

The word RASOOL:

 This word appears 116 times in the Holy Quran.

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Difference between nabi and rasul:

The titles of rasul and Nabi can be used interchangeably for prophets and messengers. It is also related that a RASOOL is also a Nabi but a Nabi may not be a rasool. A RASOOL is the one who is sent with the Book, in written or oral form, by Allah. The Prophet Muhammad is both a rasul and a Nabi.