“Thunder” is a song by British singer and songwriter Leona Lewis from her upcoming fifth studio album, I Am (2015). The third single from the album, it was released on 24 July 2015, by Def Jam. The song will serve as the lead single in the American market. Lewis co-wrote the song in collaboration with Toby Gad. Lyrically, “Thunder” is about finding the “strength of rising after the fall”.