The CI

Defines Central Illinois. Coined by two private audience improv comics/freestyle rappers known as "My 2 Dads" or "M2D" at Eastern Illinois University in 2001

Confidential Informant; Any individual under the direction of a police officer who furnishes information about criminal activity with or without compensation; works under direction of the department; different from other concerned citizens or complainants not working under department direction and not party to the investigation itself.

Short for "cisgender" (opposite of "transgender"), used to describe someone whose gender identity matches their anatomical gender at birth.

Occasionally used derogatorily.

Commonwealth of Independent States; putative successor to the USSR, except that the Baltic Republics of Estonia, Latvia, and Lithuania never joined. Contrary to another definition of CIS at the Urban Dictionary, the CIS does not stand for "Communist Independent States." Moreover, that definition has the CIS existing BEFORE 1991, and includes Kazakhstan as "not officially part of the Soviet Union." Kazakhstan was, in fact, one of the 15 republics of the USSR until 1991.

The CIS came into being December 1991. Mostly consists of regularly scheduled conferences of foreign ministers and defense ministers.

In 1995, members Belarus and Russia created the Commonwealth of Sovereign Republics (CSR).

Abbreviation for the Confederacy of Independant Systems. Second worst faction in the Star Wars universe beaten only by the wretched Alliance to Restore the Republic/New Republic as THE worst.

Cisgender (opposite for transgender). People who like the gender they were born with.

CIS is an abbreviation for the term "Collective Information Source".

A collective information source is an educational resource with information specific to a certain subject; it is usually held in a binder or folder.

A CIS can be created for general educational purposes, as a place to gather ones arguments during a disagreement, or out of pettiness.

This abbreviation is not to be confused with any of the following:
Cisgender, The Center for Immigration Studies, The Commonwealth of Independent States, The Council of International Schools, The Center for Internet Security, Canadian Interuniversity Sport, The Corpus Inscriptionum Semiticarum, Carcinoma in situ, The Center for Comparative and International Studies, The Knabenchor collegium iuvenum Stuttgart, a continuous ink system, a copper indium selenide solar cell, a contact image sensor, The Confederacy of Independent Systems, the towns in Italy and Poland, the mathematical function, the Cis beetle, cis regulatory elements, cis isotope alkenes, cisalpine, and the C# music note.