It's HISPANIC.

When referring to people of Spanish descent, if you absolutely must group them together, you should refer to them as Hispanic.

Not Spanish - unless they're from Spain.

Not Latin - unless you're trying to group them in with Italians, Greek, Portuguese, French, and Russians.

Not Latino - unless the rest of your sentence is in Spanish, or you yourself are Hispanic (and maybe you're grouping them with other non-spanish-speaking people of Latin-America, such as Brazilians).

And not Chicano - unless they're Mexican. (Chicano comes from the word Mexicano, Spanish for 'Mexican.' The X in Spanish can be pronounced like an 'H' or like a 'Ch.' So Mexicano was shortened to Xicano, and eventually Chicano.)

His·pan·ic
adj.

1. Of or relating to Spain or Spanish-speaking Latin America.
2. Of or relating to a Spanish-speaking people or culture.

n.

1. A Spanish-speaking person.
2. A U.S. citizen or resident of Latin-American or Spanish descent.

Simple. Clear. Correct.

Though you should really just be specific: Cuban, Panamanian, Dominican, Venezuelan, Mexican, Colombian, Puerto Rican, Peruvian, Honduran, Chilean, Argentinean... If you want to refer to the region, there's South American, Central American, Caribbean... But ultimately, try not to lump people together unecessarily. Think about how much people from New Zealand and Fargo and Alabama and Boston and Vancouver have in common.

(There are, of course, differing opinions on the subject. Some believe that Hispanic is of Spanish descent but Latino adds Spaniards and Portuguese to the mix. Others believe that Hispanics are white and Latinos are brown. To me, this is ridiculous and almost racist. But as you have just finished reading my take on it, you now know what's up. Many, including these boricuas (Puerto Ricans), tend to agree with me.)