Here is a definition according to the scholastic Handbook of Texas:
"According to one explanation, the pre-Columbian tribes (Aztecs) in Mexico called themselves Meshicas, and the Spaniards, employing the letter x (which at that time represented a “sh” and “ch” sound), spelled it Mexicas. The Indians later referred to themselves as Meshicanos and even as Shicanos, thus giving birth to the term Chicano."
Therefore, the term stuck to all Americans of Mexican decent. Sometimes, the word “Chicano” can be applied to a Mexican national who was brought to the United States at a very early age and adapted the “Chicano” lifestyle.
Homie: No. El Ramon es Chicano porque nacio aqui en los Estados Unidos pero es Mejicano por sangre. Le dicen el Monchi. Trucha guey! No le digas pocho.
2. A political, socioeconomic and cultural paradigm acquired from knowledge and interpretation of literature, music, politics, etc. of descendants of the Americas.