Il Nido. 4712 Wisconsin Ave. NW. 363-2672. Hours: Monday through Friday, 11:45 a.m. to 2:45 p.m. for lunch; Monday through Sunday, 5:30 p.m. to 10:30 p.m. for dinner. Atmosphere: Sophisticated, elegant, cozy nest. Price Range: Pastas are $6 to $7.50; meat, fish and chicken entrees are $7.95 to $10.50. Reservations: A necessity. Credit Cards: Accepts major credit card. Special Facilities: Accessible to patrons in wheelchairs; not a place to expect high chairs or booster seats. Parking is where you find it on Wisconsin Avenue.

There comes a time in the life of every family when dinner out means some place special - more prestigious than the local pizza parlor and more refined than a hamburger joint.

When such a need arose in our family, we thought Il Nido, a new Italian restaurant, might be the elegant but reasonable kind of place we were looking for.

Il Nido means the nest, and the image is just right: cozy, warm, nurturing, sympathetic to the young.

Our children donned their best clothes and brushed up on their very best manners: Il Nido is not the kind of place where you wander in wearing jeans.

We had made reservations and when we arrived we were seated with care and attention. Our waiter approached, ready to answer all questions. His description of dishes listed on the menu with their mysterious noms de plume was pure poetry. His dulcet tones caressed such ordinary words as "sautee" so that the pastas sounded as though they had wings and a simple veal with lemon sounded like ambrosia.

We hated to put a damper on the exhibition, but our request for children's portions or a children's menu cast a pall on the recitation. Rallying, our waiter asked the headwaiter and came back with the answer: Half portions of pastas were available at half price.

We started with Tagliatelle ai funghi (egg noodles with mushrooms) to share as an appetizer. The tagliatelle, $7.50, had been strongly recommended by our waiter and it seemed like a good idea.

Once served, the idea was even better: The homemade noodles were rich and firm, the creamy sauce announced its presence softly while the mushrooms added a counterpoint. Each of us had only a smattering of noodles and a teasing of mushrooms, but it was a good way to start.

Service was leisurely, as befits a restaurant intent on serving dinner rather than turning over tables, and we didn't mind the wait for our main courses. The bread with ample supplies of butter was only fair, but there were no signs of restlessness among our nestlings.

Our children had decided to share a portion of Bavette alle vongole, $6.95. Freely translated, this dish was linguine with clam sauce and a few other bits of interesting seafood thrown in. They has originally requested Timballo alla Teramana, $6.95, a lasagna, but it was not available that night.

The Bavette was a more than adequate substitute. The linguine was fully packed. The cream sauce was similar to that in our dish of Tagliatelle, but the clam and seafood mixed in and among it made all the difference. Although the headwaiter had suggested that half a portion might not be enough of a main course, our children found it more than adequate, coming as it did after their share of Tagliatelle, several slices of bread and generous tastes of their parents' dishes.

My husband splurged on a special of the day, Zuppa di pesce, $10.95, a beautiful and well-seasoned melange of clams, mussels, sea bass and other seafoods in a lovely red broth.

I had been won over by the waiter's siren song for the Piccatina al limone, $8.50. The veal melted at the touch and was beautiful to see and taste. My only objection: The portion was quite small. However, It was accompanied by a marvelous serving of zucchini and that helped.

For dessert, we eyed the whipped cream concoctions on the dessert tray, but our waiter was upon us, describing "semi-frio," a semi-soft ice cream that was part vanilla, part orange in flavor. Topping the ice cream was an orange liqueur sauce. Even our children couldn't resist - and orange liqueur is far from their favorite.

The semi-frio, $2.50, which we shared four ways, was the perfect light and refreshing ending to our meal. The crisp orange flavor and cool ice cream had us debating about a second order. We resisted in the interest of economy. As it was, the bill of our special, elegant dinner came to $36.40. For that we found food that was excellent and service and ambience that was of an elegance and style that does not often come our way.