How does one describe the nearly 11 million people living in the United States without proper documents?

In 2010, Latinos and immigration activists marched in Phoenix to protest SB1070, which was termed as the "show me your papers" law. One sign said, "No human being is illegal."

Over the years, a dispute has risen on the proper term to be used in describing undocumented immigrants.

Otto Santa Ana, a linguist and professor in the University of California's Department of Chicana/o Studies, and other linguists said using the phrase "illegal immigrants" is neither "accurate nor neutral," reported The Guardian.

"We don't call pedestrians who cross in the middle of the road illegal pedestrians," he said. "A kid who skips school to go to Disneyland is not an illegal student. And yet that's a sort of parallel."

Democratic presidential candidate Hillary Clinton became involved in the issue during a Facebook Q&A when Pulitzer-prize winning journalist and immigration activist Jose Antonio Vargas asked her to stop using "illegal immigrant."

He said Clinton used the term at a New Hampshire campaign event. Clinton admitted that it was a "poor choice of words" and promised not to use the phrase again.

"As I've said throughout this campaign, the people at the heart of this issue are children, parents, families, DREAMers. They have names, and hopes and dreams that deserve to be respected," she said.

Vargas, an undocumented immigrant, was surprised to hear Clinton use the phrase as she made immigration a major programme in her campaign.

"I am here illegally, without legal status, without authorisation. Those are facts. I as a person am not illegal because people can't be illegal. Calling people illegal is not only factually inaccurate, it's journalistically irresponsible," said Vargas who came to the U.S. from the Philippines as a child.

Vargas recently launched the #WordsMatter campaign aiming to encourage all the 2016 presidential candidates to drop the phrase "illegal immigrants."

Former Maryland governor Martin O'Malley, another Democratic presidential candidate, decried Clinton's use of the phrase and joined the campaign.

"I have always called immigrants New Americans because that is what they are," he said.

Republican candidate Donald Trump often includes "illegal aliens" in his speech, which activists say is offensive.

Jeb Bush was criticised for using the term "anchor babies" to describe children who are born in the U.S. to undocumented parents.

José Luis Benavides, a journalism professor at California State University, Northridge, said for many Americans, "illegal immigrant" is synonymous with Mexican, and specifically someone who crossed the U.S. southern border unlawfully.

Since 2008, the report said, more immigrants overstayed their visas than crossed the U.S. border legally. In the last five years, more immigrants returned to Mexico from the U.S. than migrated north.

Almost 11 percent of the undocumented population in the U.S., or 1.3 million, are from Asia.