Pandiatonicism refers to the use of all diatonic notes without the need for scale degrees or harmonies to progress or function tonally (V doesn’t need to progress to I, $\hat{7}$ doesn’t need to resolve to $\hat{8}$ , etc.). One often hears it as a wash of notes from the major scale, or as chords made of non-traditional combinations of notes from a major scale, often with at least one interval of a 2nd in a chord voicing.