Cynthia's daughter, Dr. Jenn Mann, tells TMZ ... "My mother, Cynthia Weil, was the greatest mother, grandmother and wife our family could ever ask for. She was my best friend, confidant, and my partner in crime and an idol and trailblazer for women in music."

Jenn says her mother, a Rock and Roll Hall of Fame inductee, passed on Thursday night.

Cynthia's catalog is eyepopping ... The Righteous Brothers' "You've Lost That Lovin' Feelin," Dolly Parton's "Here You Come Again," The Drifters' and George Benson's "On Broadway," The Crystals' "Uptown," The Righteous Brothers' "You're My Soul and Inspiration," The Animals' "We Gotta Get Out of this Place."

The list just keeps going, with Paul Revere & the Raiders' "Kicks," The Ronettes' "Walking in the Rain," Chaka Khan's "Through the Fire," which Kanye West sampled for his debut solo single, "Through the Wire" ... and that's a VERY short list of the hits she wrote.

Cynthia's writing partner for many of her hits was her husband, Barry Mann. They were married for 62 years.

They were nominated for an Academy Award and won 2 Grammys for Linda Ronstadt and James Ingram's "Somewhere Out There" from Steven Spielberg's "An American Tail."

She and Barry received the first-ever National Academy of Songwriters Life Achievement Award.

In her early years, Cynthia was an actress, singer and dancer and became a protégé of Tin Pan Alley songwriter Frank Loesser.

Cynthia and Barry had massive hits in the '60s, '70s, '80s and '90s.

She worked with other collaborators to produce hits like "Running With The Night" and "Love Will Conquer All" with Lionel Richie. She also worked with David Foster for the soundtrack to "St. Elmo's Fire," including the hit, "For Just a Moment." And then, there's Peabo Bryson's "If Ever You're In My Arms Again,” and "He's So Shy" by The Pointer Sisters.

BTW ... "You've Lost That Lovin' Feelin'" was the most played song of the 20th Century!

Cynthia received 112 pop, country and R&B awards from BMI.

Cynthia and Barry produced another big hit ... their daughter, Jenn Mann, AKA Dr. Jenn, a psychotherapist, author, and host of VH1's "Couple's Therapy." Jenn and her fiance Eric Schiffer were by Cynthia's side when she passed.

The family adds, "Cynthia Weil's Grammy award winning lyrics touched the hearts and souls of hundreds of millions of people around the world, making her one of the most iconic songwriters of the 20th Century. Her husband, Barry Mann, says, "I'm a lucky man. I had two for one, my wife and one of the greatest songwriters in the world, my soul and inspiration."

Cynthia was 82.