parting vs unison

parting

noun
  • The surface of the sand of one section of a mould where it meets that of another section. 

  • A joint or fissure, as in a coal seam. 

  • The dividing line formed by combing the hair in different directions; part (US) 

  • The separation and determination of alloys; especially, the separation, as by acids, of gold from silver in the assay button. 

  • A farewell, the act of departing politely. 

  • The breaking, as of a cable, by violence. 

  • Lamellar separation in a crystallized mineral, due to some other cause than cleavage, as to the presence of twinning lamellae. 

  • The act of parting or dividing; the state of being parted; division; separation. 

unison

noun
  • A sound or note having the same pitch as another, especially when used as the base note for an interval; a unison string. 

  • The state of being in harmony or agreement; harmonious agreement or togetherness, synchronisation. 

  • Identical pitch between two notes or sounds; the simultaneous playing of notes of identical pitch (or separated by one or more octaves). 

  • Two or more voices speaking the same words together. 

How often have the words parting and unison occurred in a corpus of books? (source: Google Ngram Viewer )