My two college-age daughters were horrified when their 45-year-old aunt got her belly button pierced. They say they’ll remove their belly rings when they have children, because it’s "inappropriate" for moms to wear them. They also think women my age (53) are too old to wear fitted jeans with sexy tops and pointy mules. The irony is that they couldn’t wear jeans wherever they like if it weren’t for our generation: We broke the rules on appropriate dressing decades ago.What does age-appropriate dressing mean to us now? My friend Tessa, a glamorous 53-year-old personal trainer, bristles when she sees her contemporaries baring their midriffs off the beach or dressing like their daughters. "I don’t care how fit these women are," she says. "Their faces don’t match their clothes."My 50-year-old sister, Jill, has a boyfriend who likes to see her in short skirts. She’s not sure she’s comfortable wearing them, even through her legs are great. My friend Marilyn, who has spent her entire career in the style business, is starting to doubt her own fashion sense. "Sometimes I wonder if I’m a crazy retro-chic throwback stuck in the 1950s," she says. "There’s something creepy about wearing the same styles you wore when you were younger, like peasant tops — especially if your daughters are wearing their version of them. Instead of looking cool, I’m afraid I look like I never moved on."Should we care what others think at this stage of our lives? The style-confident women I know say that the idea of age-appropriate dressing has no meaning for them; it’s more about body-appropriate dressing. My friend Susan, an independent, creative mother of four, recently did a major purge of the dowdy clothes in her closet, most of which her mother had given her. "I kept them for years, thinking I would wear them when I turned 50," she says. "But 50 came and went, and I realized they still look dowdy — and I don’t."Our generation is redefining the concept of aging, just as we’ve redefined everything else. Style after 40 is not about competing with your daughters or dressing like the girl you were 20 years ago; it’s about dressing like the girl you are now. If you prefer a scoop neck or a short skirt, how much of you you show is your decision. What really matters is that you feel as comfortable in your clothes as you do in your skin.On a recent holiday in Saint Barts, a mecca for the barely dressed and ultra-body-confident, I wore the only two-piece bathing suit I own, covered with various sarongs. Anything more, and I would have felt like I was hiding in a snowsuit. When my daughters protested, I told them, "When in Saint Barts, I’ll wear a two-piece or no-piece." I don’t always agree with their expectations of how I should look, but I do listen to them. They shake me loose from my assumptions and encourage me to experiment with new styles.This summer, I’ll dress with a watchful eye on what flatters my body now. My legs are still in great shape but are no longer evenly pigmented, so I’ll need longer skirts or pants unless I want to wear stockings, which I don’t. That’s the real trick to age-appropriate dressing: Once you’ve looked at yourself honestly and figured out what works best on you now and what no longer suits you, you’ll feel more confident in what you choose to wear.What to Wear…...When Your Arms Are Toned but Your Middle Isn’tThis stretch-cotton ribbed tank by Hugo, $85, is thick and shapely enough to hide a support bra. And the white wool boucle pencil skirt by Escada, $550, sleekly accommodates curves. Come fall, you’ll wear it with a black turtleneck and boots. But for now, just add leg-lengthening wedges like these by J. Crew, $158. The wide Hugo belt, $195, adjusts to sit at the waist or top of the hip. Ted Rossi snakeskin clutch, $350. Morgenthal Frederic titanium-and-tortoise aviators, $485. Viv & Ingrid necklace, $86.What to Wear…...to Look Chic when You’re Not Feeling SleekJ. Crew’s flattering linen tunic, $350, is on our gotta-get list, because we’ll literally wear it through thick and thin. It also has great day-to-evening potential. Layer it over summery whites — long peasant skirts, crisp flat-front pants, or casual capris, like these from Theory, in cotton poplin, $200. Mossimo for Target sunglasses, $13. Kors thongs, $93.