Wednesday was the national day of awareness for the R Word Campaign, the effort to persuade the world that “retard” and “retarded” have no place in polite conversation. Supporters of the campaign — count me among them — would have you replace either of those with a different R word: respect.

The R word, as any parent, sibling or friend of someone with an intellectual disability can tell you, is about as hurtful as a word can be. It’s used in casual conversation not to define a medical diagnosis, but to belittle or otherwise insult someone. It doesn’t tell you that someone is an exceptionally coordinated dancer or is particularly good at math; in fact, just the opposite.

As such, it’s something of a throwback, a word that, along with such niceties as “Mick” or “Wop,” used to dot too much of American language. Fortunately, many of those old pejoratives have disappeared. Unfortunately, the R word lingers.

I don’t know why.

I don’t think Americans are, by definition, a mean-spirited people. Most of us would never dream of intentionally hurting another’s feelings, particularly about something he has no ability to change. Ethnicity is one of those things. Such things as limps or the need to wear glasses are others. Intellectual disability falls into that category, as well.

Ann Coulter, the conservative columnist, found herself under attack last fall for using the R word about President Barack Obama. She later defended her choice of words, saying that she would never use the word directly to someone with an intellectual disability. Besides, she said on a Fox News radio program, “‘Retard’ has been used colloquially to just mean ‘loser’ for 30 years.”

And that, of course, is just what’s wrong with the word. It’s meant to brand someone as a loser, and in so doing, it brands an entire group of people as losers just by being.

Long before I knew my daughter Mary — who was born with Williams Syndrome, a condition that leaves her intellectually disabled — I thought taking such care with language had become an act of political correctness, that people thus insulted were probably being oversensitive and should just toughen up. After all, no insult was meant and, therefore, none should be taken.

But, of course, insult is taken about the R word, just as it is about slurs like “four-eyes” or any of a dozen casual definitions of ethnicity or skin color. It is taken because listeners know that, despite our protests, insult is meant.

One of the cable television networks is in the midst of what can best be described as a tolerance campaign, an effort, in part, to make viewers aware that labels and language do matter. They do, I think, because they influence the way we think about and treat other people.

When we insult those around us by calling them names, we give ourselves permission to treat them as something less than equals. We dehumanize them in the process, and that makes it easy to deny them the right to a full role in society. It doesn’t matter if the insult comes in the form of the R word or a word about sexuality or place of birth.

Language is a potent weapon in this world. We praise a child for his actions, tell him how smart or kind or wonderful he is, and he blossoms. He knows he is valued, that he counts for something.

Call him a demeaning name and we get the opposite reaction. We can, if we’re observant, see him shrink before our very eyes. We’ve told him, in effect, that he’s not important, that he doesn’t count for much.

I don’t know why anyone would do that to a kid. By the same token, I don’t know why anyone would do that to an adult or group of adults, intellectually disabled or not.