From together +‎ -ness.

togetherness (countable and uncountable, plural togethernesses)

1. (uncountable) The state or quality of being together.
   • 2005, Kimberly Joyce, Pretty Persuasion:

     My hope is that the fair will not only raise money for the drama club, but also - kind of - foster a spirit of togetherness among the multicultural community here at Roxbury.

   • 2016 June 27, Daniel Taylor, “England humiliated as Iceland knock them out of Euro 2016”, in The Guardian‎^[1], London:

     Iceland played with courage, skill and togetherness and might also fancy their chances against France in Sunday’s quarter-final.

2. (countable) The result or product of being together.

• collectedness, community, unity

• disarray, disunity, uncollectedness, untogetherness, aloneness