Prince William's super sweet nickname for Princess Charlotte has been revealed in new family video

After a couple of weeks of nonstop "awwww" moments from the royal family, once again they are melting our hearts.

This time it is the beautiful French nickname the Duke of Cambridge has given his daughter, Princess Charlotte.

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In an adorable family video released by Kensington Palace this week, Prince William can be heard lovingly referring to the four-year-old with the moniker as they share an intimate moment on a swing in Kate Middleton's RHS 'Back to Nature' Garden at the Chelsea Flower Show.

Can you hear what William calls Charlotte in this video?

It turns out the father-of-three calls his only daughter "Mignonette", which is a derivative of the French word 'mignon' - meaning dainty or darling.

In English, it would be the equivalent of saying 'cutie' or 'sweetie'.