From the same as 'em; a collection, i.e. Community of persons -- nation, people.
see HEBREW 'em
H523. ummah
[אֻמָּה] noun feminine tribe, people (Arabic ; Assyrian ummatu compare JenKosmol. 336, Aramaic , אוּמָּא) only plural אֻמּוֺת Numbers 25:15; אֻמִּים Psalm 117:1; suffix אֻמֹּתָם Genesis 25:16; — of tribes of Ishmaelites 25:16; of Midian ("" בֵּיתאָֿב) Numbers 25:15; "" גּוֺיִם Psalm 117:1.
אֻמָּה noun feminine nation (Biblical Hebrew id., late); — absolute ׳א Daniel 3:29; plural emphatic אֻמַּיָא 3:4, 7; Daniel 3:31; 5:19; 6:26; 7:14; Ezra 4:10.