Praise be to Allaah.

Shaykh Muhammad al-Ameen al-Shanqeeti (may Allaah have mercy on him) said: 

The word ummah is used in four senses in the Qur’aan: 

1 – The word ummah is used to mean a period of time, as in the aayahs (interpretation of the meanings): 

“And if We delay the torment for them till a determined term [ila ummatin ma’doodah]”[Hood 11:8] 

“Then the man who was released (one of the two who were in prison), now at length [ba’da ummatin] remembered”[Yoosuf 12:45]

2 – It is used to mean a group of people, which is the usual usage, as in the aayahs (interpretation of the meaning): 

“he found there a group of men [ummatan min al-naas] watering (their flocks)”[al-Qasas 28:23] 

“And for every Ummah (community or nation) there is a Messenger”[Yoonus 10:47] 

“Mankind were one community [ummah]”[al-Baqarah 2:213]

and there are other similar aayahs. 

3 – The word ummah is used to refer to a man who is taken as a leader, as in the aayah (interpretation of the meaning): 

“Verily, Ibraaheem (Abraham) was an Ummah (a leader having all the good righteous qualities)”[al-Nahl 16:120]

4 – The word ummah is used to mean a way or religion, as in the aayahs (interpretation of the meanings): 

“They say: “We found our fathers following a certain way and religion [ummah]”[al-Zukhruf 43:23]

“Truly, this, your Ummah [Sharee‘ah or religion (Islamic Monotheism)] is one religion”[al-Anbiyaa’ 21:92]

and there are other similar aayahs.