Contraction of latinoamericano, the Spanish word for Latin American. The feminine form is latina. Anyone from a country in Latin America (Mexico, most of Central and South America, Cuba, Puerto Rico, and the Dominican Republic) or with heritage and ancestry from Latin America is a Latino/Latina.
Jennifer Lopez is of a Puerto Rican background; she is a Latina.
Christina Milian is of Cuban background; she is a Latina.
Cesar Chavez is of Mexican background; he is a Latino.