The terms "Chicano" and "Chicana" (female, also spelled "Xicana") are used in reference to U.S.

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 citizens of Mexican

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

 descent. However, those terms have a wide range of meanings in various parts of the world. The term began to be widely used during the Chicano Movement

Chicano Movement

The Chicano Movement of the 1960s, also called the Chicano Civil Rights Movement, also known as El Movimiento, is an extension of the Mexican American Civil Rights Movement which began in the 1940s with the stated goal of achieving Mexican American empowerment.-Origins:The Chicano Movement...

, mainly among Mexican Americans, especially in the movement's peak in the late 1960s and early 1970s. For Mexicans, the meaning of "Chicano" meant "poorest of the poor" but during the Civil Rights movement, they used the word to unite themselves.
The origin of the word "chicano" is disputed.