Bill Cosby Sued for Allegedly Drugging and Raping Accuser Donna Motsinger

4:45 PM PT -- Bill Cosby's rep, Andrew Wyatt, tells TMZ … “No comment at this present time because this is utterly ridiculous and pointless.”

Bill Cosby is being sued by one of his accusers for an alleged sexual assault ... one she claims happened over 50 years ago.

According to a new lawsuit, obtained by TMZ, Cosby accuser Donna Motsinger claims he took advantage of her way back in 1972, when she was working as a server at the famous Trident restaurant in Sausalito, CA.

Motsinger says she met Cosby at the bayside restaurant, then a celeb hangout, claiming he came by constantly just to see her, ultimately inviting her to accompany him to his show at the Circle Star Theater in San Carlos.

In the docs, Motsinger says Cosby picked her up in a limo and gave her a glass of wine on the drive over. She claims he took her to the dressing room, where she began to feel sick and says Cosby gave her what she believed was an aspirin.

Motsinger says she took the pill and started falling in and out of consciousness. She claims Cosby's handlers but her back in the limo with him and the last thing she remembers was flashes of light.

In her suit, Motsinger claims she woke up in her house wearing only her panties and says she "knew she had been drugged and raped by Bill Cosby."

Motsinger says she's suffered mental, physical and emotional distress ... and she's going after Cosby for money.

She previously came forward in 2014 with similar accusations against Cosby ... and now she's followed up with a lawsuit.

We reached out to Cosby's camp ... so far no word back.