A karass of only two people, who are so bound together that even their children cannot invade their union. From Kurt Vonnegut's "
Cat's Cradle." (A karass is a
group of people bound together, often without externally discernable
ties.)
From "Cat's Cradle":
“They were lovebirds. They entertained each other endlessly with little gifts: sights worth seeing out the plane window, amusing or instructive bits from things they read,
random recollections of times gone by. They were, I think, a
flawless example of what Bokonon calls a duprass, which is a karass composed of only
two persons.”