You may not have heard of Rosa’s Law, but when my daughter Mary learned about it earlier this week she gave the news one of those arm-pumping whoops that signal victory these days. No wonder. Once the bill, which sailed through both houses of Congress virtually without argument, is signed by President Obama, she’ll be rid of the hurtful but official designation “mentally retarded” and become what she calls herself, “intellectually disabled.” It’s about time.

Mary’s reaction to the phrase and to the single word “retarded” has been my only real experience with the pain such words cause those at whom they’re aimed, and it’s been a real eye opener. No matter the saying about sticks and stones, words do hurt.

The government’s usage aside, “retarded” is an epithet that crosses all racial and social lines in a way few other epithets do. It’s used against people, actions and even situations, and almost never is the implication positive. Like other words, its dictionary meaning and its social one are similar but far from identical.

The government’s definition of mental retardation is actually pretty straightforward. It applies to a person whose IQ is 70 or less and who has some other deficit that makes independent daily functioning difficult. Generally, those problems have been with the individual since birth or very early childhood.

It’s an important definition. Fall on one side of it — have the low IQ but no other limitation — and you may qualify for assistance in school but will find that service ends once school does. That may well be fair: If you can hold a job, rent a house and make the daily judgments required to get along in the world, you likely do not need help through adulthood.

Fall on the other, and it’s a different story. Special education services are available to every child who needs them to age 21, but for those tagged mentally retarded services can be available for a lifetime.

In school many are likely to spend lots of time on what are called “life skills,” learning to shop, manage public transportation and hold a job. They spend far less time than their peers on academic subjects, though Mary’s experience convinces me that many could do far more academically than they are asked. The never-stated reason for the shifted emphasis is simple and logical from the government’s point of view: The more independently the intellectually disabled can live, the less society will have to spend on supporting them.

Still, if I have reservations about the state of education for the intellectually disabled today, it’s come light years since the Education for All Handicapped Children law was enacted in 1975. Before PL 94-142, as it was known, was put in place, kids with intellectual disabilities were generally relegated to the back of whatever school building they were in, isolated from the “normal” population.

Not surprisingly, the idea that they could actually contribute to society was considered far-fetched, and their treatment in the school systems of this country pretty much assured they’d be greeted with giggles and even fear most of their lives. It was then, I suspect, that “retard” took on the hurtful meaning it has today.

That’s changed, thank goodness, and Rosa’s Law chips away further at the aftereffects of that earlier time. The law is the work of Sen. Barbara Mikulski, D-Maryland, in honor of Rosa Marcellino, a sparkly little 8-year-old with Down syndrome.

The law brings the language in federal law in line with the language used by the Centers for Disease Control and the United Nations, but it does nothing to change the way the government treats those with intellectual disabilities.

No law will persuade people that “retarded” and “retard” are as unacceptable as the “n” word — that will take more work by the “Spread the Word to End the Word” campaign and others — but at least it means the epithet is no longer an official government designation. That’s a start. Not a huge one, perhaps, but a start. Now it’s up to just plain folks to do the rest.