She died peacefully at her home after a long illness, her manager Devra Hall Levy said.
The jazz vocalist from Ohio made her debut with her 1961 single Guess Who I Saw Today.
Her biggest hit was in 1964 with (You Don’t Know) How Glad I Am, which hit the Billboard chart at number 11 but also earned her a Grammy Award for best R&B recording.
John Legend called her a “magical performer,” while jazz writer Nate Chinen called her “incomparable”.
He wrote on Twitter:
“The bell-like clarity of her tone, the unerring sense of phrase. Her rare gift for evoking a world of narrative possibility with a few lyrical gestures. Majesty and modernity, with suave to spare.”
The singer’s namesake – Nancy Wilson of US rock band Heart also tweeted her sympathies, saying “she did a great thing in the world”.
Written By: By Kev Geoghegan & Paul Glynn
First Published 14.12.18: https://www.bbc.co.uk/news/entertainment_and_arts