Karass is a group of people who are (often unknowingly) associated with each other for purposes beyond their immediate comprehension. They may be thought of as the fingers supporting a web of yarn.
The concept of a karass is central to Bokononism, which is a religion founded by Bokonon. Bokononism is the chief religion of San Lorenzo, which is a fictional Caribbean island nation in Kurt Vonnegut, Jr.'s novel Cat's Cradle.
In a way that would surely please old Vonnegut, karass has become a part of our collective consciousness and has been fittingly used to describe social network analysis.
There is also a band from Louisville, Kentucky called Karass. They have one full-length release (Or Granfalloon) and one remix EP (My Robot Can Beat Up Your Honor Student). Their sound is synth-y post-rock with jazz overtones reminiscent of Tortoise or Holy Fuck.
Karass is also the name of two corporations. One of which is a public relations firm out of Seattle which "bonds brands to tribes". Their mascot is a bear. The other KARASS is a firm founded by Dr. Chester Karass which offers training seminars for effective negotiations.
The opposite of a karass is a granfalloon, which is a group of people who share an imaginary or accidental connection—such as having a place of origin or school in common.
Naturally we are left to wonder how these two concepts apply to our own lives. Which parts of which things are which we may never now—wiser heads have said that some things can be both karass and granfalloon—but that there exists a net beyond what we know to be seems certain.