### Find the word definition

##### Wiktionary
subring

n. (context algebra English) a ring which is contained in a larger ring, such that the multiplication and addition on the former are a restriction of those on the latter

##### Wikipedia
Subring

In mathematics, a subring of R is a subset of a ring that is itself a ring when binary operations of addition and multiplication on R are restricted to the subset, and which shares the same multiplicative identity as R. For those who define rings without requiring the existence of a multiplicative identity, a subring of R is just a subset of R that is a ring for the operations of R (this does imply it contains the additive identity of R). The latter gives a strictly weaker condition, even for rings that do have a multiplicative identity, so that for instance all ideals become subrings (and they may have a multiplicative identity that differs from the one of R). With definition requiring a multiplicative identity (which is used in this article), the only ideal of R that is a subring of R is R itself.

#### Usage examples of "subring".

Trantor is in the innermost subring of the spiral arms and, believe me, if you could see its night sky, you would think it was in the center of the Galaxy.

Some of the subrings are not quite circular and at least one seems to be braided.