Inversion refers to the re-positioning of the notes of a chord. If the root is the lower-most note, the chord is said to be in root structure. If the 3rd is the lower-most note, it is said to be in ‘first inversion’, i.e. the root has been placed in an upper voice leaving the 3rd as the lower-most note (voice), and is traditionally indicated ‘6’ because of the interval from the 3rd to the root. Inversion in the spoken language refers to the re-positioning of the words in a phrase; e.g. “You are happy”, inverted – “Are you happy?” See ‘figured bass’.