Universal Integrated Circuit Card definition in Computer Security terms:
Definition(s): An integrated circuit card that securely stores the international mobile subscriber identity (IMSI) and the related cryptographic key used to identify and authenticate subscribers on mobile devices. A UICC may be referred to as a: SIM, USIM, RUIM or CSIM, and is used interchangeably with those terms.
Source(s): NIST SP 800-101 Rev. 1
reference: CSRC Glossary