I’ve heard the names my whole life: Grandma, Grampy, Mimi, Bube, Grandpa, Papa, Nonna. Nonny, Nana. Grandfather, Grandmother.

But I never knew these names were magic until one was said to me.

It was Nana that I called my grandmothers, Big Nana and Little Nana, because that’s what they were, not just in size, Big Nana as wide as she was tall and Little Nana petite and delicate, but in temperament, too, and in presence. Little Nana dyed her hair red and painted her fingernails the same color as her lipstick. She got dressed up, heels and all, just to hang out the laundry.

Big Nana never wore heels. She wore shoes with ties and cotton housedresses and a serious expression, even when she was telling a funny story. She worked as a waitress at a bar about a mile from her flat and when she was in her seventies and the Boston Strangler was stalking women her age, she refused to be cowed by fear and despite my parents’ pleas, continued to walk to and from her job every night.

I wonder now if they loved them, if big meant what it did to me — significant, prime, imposing. And if Little Nana knew she was as pretty and delicate as a butterfly.Big and Little. Did I give them these names? Or did my parents?

Every 20 seconds now a new grandparent is born. Which means that every 20 seconds a grown-up with a string of names — John, Jack, Mom, Dad, Buddy, Auntie — gets to pick a new one.

I picked Mimi. I chose it when my oldest daughter was pregnant with my first grandchild. I let it sit on my tongue for months. I tested it, said it out loud and savored its sweetness. I imagined a child calling me this. I conjured it in a singsong voice.

Mimi, so close to Mama, it’s a wonder my daughter allowed this choice. It’s a wonder she didn’t say, “No, Mom. Pick something else.”

I love the word. Mimi. I love hearing it and saying it and writing it and thinking it. It is my favorite name ever. There have been other names I’ve loved. My goddaughter calls me “Belle” and another young friend calls me “Aunt Beppy” and my children call me Mom and Ma. And my parents and my Aunt Lorraine used to call me Baybo, and how I would love to hear that name in their voices again. But it’s Mimi that stops me in my tracks these days, that makes my heart swell to twice its size no matter what I’m doing, that makes me strut a little. That makes me smile.

“Mimi, will you?”

“Mimi, can I?”

“Look, Mimi”

“Hi, Mimi!”

“I love you, Mimi.”

You’d think I’d remember when Lucy, my oldest grandchild, the one for whom the word was chosen, first said it. Or Adam, the next in line. But I don’t. All I know is that Charlotte, who is just 16 months, is saying it now.

She doesn’t say much. She runs. She climbs stairs. She climbs on everything. But she doesn’t talk yet. Mostly she points to what she wants and shouts, “Unk!”

But she calls me Mimi.

Thirty years ago, the U.S. government decided to honor the bond between grandparents and grandchildren so the legislators picked a day — the first Sunday after Labor Day and proclaimed it National Grandparents Day.

It hasn’t quite caught on. It’s not printed on yearly planners or on at-a-glance calendars. It’s not a big Hallmark holiday. It’s not — thank Heaven — a day that demands a gift.

“There’s a Grandparents Day?” my son said just last week.

It is a gentle surprise, this holiday.

Maybe this is because the relationship between grandparents and grandchildren is a surprise too. Who knew there could be such great love? Who knew that a simple name on the lips of a small child — Mimi, Papa, Grammy, Grampy — could jumpstart a heart?

There is so little said about this mutual love. There are no epic Gone With the Wind-type novels, very few poems, and hardly any movies and sitcoms.

“To honor grandparents. To give grandparents an opportunity to show love for their children’s children. And to help children become aware of the strength, information and guidance older people can offer.” These are the purposes of Grandparents Day.

And these are the links, honor and guidance and love, that grandparents and grandchildren share every day.