By 1990, Congress passed the Americans With Disabilities Act that outlawed many forms of discrimination against disabled people, but it wasn't until much later that terminology changed.
In 2006, the American Association on Mental Retardation voted to change its name to the American Association on Intellectual and Developmental Disabilities.
By 2008, The Associated Press struck "mentally retarded" from its stylebook -- the Bible of mainstream journalism.
"My sister might be one of the smartest kids I've ever met, and that's the truth!" Nick told legislators. "It might take her longer to learn some things, and you can't always understand everything she says. She'll never be 'just like' most people, but hopefully, neither will I."
Today, most advocacy groups use phrases like "mentally challenged" or "intellectual disability" or the broader term, which also encompasses autism and cerebral palsy, "developmental disability."
"Mental illness, more than any other disability, has gone through these iterations of names," said Donald Freedheim, professor emeritus of psychology at Case Western Reserve University in Ohio.
"It's so prevalent, kids calling kids dummies -- it's always a derogatory term," he told ABCNews.com. "We've gone through moron, imbecile to mentally sub-normal to mentally deficient. You can practically write a history of mental retardation."
And no sooner does one term change than the new replacement becomes "stigmatizing," he said.
Still, he agrees the words need to change. "It's a horrible added burden to children and families."
Ron Drabman, a clinical psychologist and former director of psychology training at the University of Mississippi Medical Center, said schools need to do more than just change words.
"Words are important, but it's more important to protect children," he told ABCNews.com. "But it's much more difficult."
And some are skeptical that a Senate vote would accomplish much.
"I am Nick," said Kris Alexander Eschauzier of Portland, Maine. "My brother Blake is 'mentally retarded' and oh, how I hated it. And I still do when people throw around those phrases such as 'retard' and 'that's so retarded.'"
"Unfortunately, I don't think changing an official government designation will do much to stop the hurt," she told ABCNews.com.
But Nina Marcellino and her family say the issue is larger than just changing the lexicon.
"It was more than words to us," she said. "We all felt like you cannot separate what you call people from how you treat people. Attitudes have been changing and everybody felt that with a new term, it was a new beginning."
ABC's Tom Shine contributed to this report.