The toponym has been explained as reflecting Old High German *ustrâ or *uster-aha "voracious [river]" by Boesch (1978).

[4] The Burg Uster (castle) was first mentioned in 1267, as being in the possession of the Freiherr von Bonstetten.

[5] On 7 January 1300 Elisabeth von Rapperswil sold the pledge of the reign Greifensee to the knight Hermann II.

von Landenberg, including the Greifensee castle, the town and the lake of the same name, and a larger number of farms, as well as the pastoral rights (Kirchrecht) in Uster.

The church was considered as a part of the so-called "Laubishof" estate that possibly was located at the nearby plateau where the Uster Castle is situated.

The town was captured after four weeks, on May 27, and all but two of the surviving 64 defenders were beheaded on the next day, including the leader, Wildhans von Breitenlandenberg.

Even in times of war, mass execution was widely considered a cruel and unjust deed.

Among many other transfers of lands and goods, on 25 April 1448 Beringer von Landemberg von Griffensee confirmed, with permission of his sons Hug and Beringer dem Jungen that at the place where all his ancestors have been buried, a long list of money, goods and lands have to be transferred to the church as a benefice.

[7] In 1473 the church comrades, based on an older Jahrzeitbuch (Latin: libri anniversariorum) which now is lost, created a new one which is among the best preserved of the Canton of Zürich.

[4] On 22 November 1830 about 10,000 men of the canton of Zürich gathered near Uster and demanded a new constitution.

Of the rest of the land, 26.2% is settled (buildings or roads) and the remainder (2.3%) is non-productive (rivers, glaciers or mountains).

The wettest month is June during which time Uster receives an average of 137 mm (5.4 in) of precipitation.

Nänikon-Greifensee railway station is on the border with adjoining municipality of Greifensee, and is served only by lines S9 and S14.