The word Ummah is used in the Qur'an and Sunnah with a number of different meanings. Sometimes when it is used it means a specified period of time:
إِلَى أُمَّةٍ مَّعْدُودَةٍ
Till a determined Ummah (term)
This is also the meaning in the statement of Allah in Surah Yusuf:
وَقَالَ الَّذِى نَجَا مِنْهُمَا وَادَّكَرَ بَعْدَ أُمَّةٍ
Then the man who was released, now after Ummah (some time) remembered. [12:45]
The word Ummah is also used to refer to the Imam (leader) who is followed:
إِنَّ إِبْرَهِيمَ كَانَ أُمَّةً قَـنِتًا لِلَّهِ حَنِيفًا وَلَمْ يَكُ مِنَ الْمُشْرِكِينَ
Verily, Ibrahim was an Ummah, obedient to Allah, Hanif, and he was not of those who were polytheists. [16:120]
The word Ummah is also used to mean religion and religious creed. Allah mentions the polytheists said:
إِنَّا وَجَدْنَآ ءَابَآءَنَا عَلَى أُمَّةٍ وَإِنَّا عَلَى ءَاثَـرِهِم مُّقْتَدُونَ
Verily, we found our fathers following a certain way and religion, and we will indeed follow their footsteps. [43:23]
The word Ummah is also used to mean a group (of people).
وَلَمَّا وَرَدَ مَآءَ مَدْيَنَ وَجَدَ عَلَيْهِ أُمَّةً مِّنَ النَّاسِ يَسْقُونَ
And when he arrived at the water (well) of Madyan, he found there a group of men watering (their flocks).[28:23]
وَلَقَدْ بَعَثْنَا فِى كُلِّ أُمَّةٍ رَّسُولاً أَنِ اعْبُدُواْ اللَّهَ وَاجْتَنِبُواْ الْطَّـغُوتَ
And verily, We have sent among every Ummah a Messenger (proclaiming): "Worship Allah (Alone), and avoid Taghut. [16:36]
وَلِكُلِّ أُمَّةٍ رَّسُولٌ فَإِذَا جَآءَ رَسُولُهُمْ قُضِىَ بَيْنَهُمْ بِالْقِسْطِ وَهُمْ لاَ يُظْلَمُونَ
And for every Ummah there is a Messenger; when their Messenger comes, the matter will be judged between them with justice, and they will not be wronged. [10:47]
The meaning of Ummah here is the nation who has had a Messenger to them, including believers and disbelievers among them.
