onesome

plural onesomes

1. rareA solitary person or thing; a "group" of one.

   When Joe and Suzie left, the threesome became a onesome.

   1 more example

   The remote innocence of the time may be read not only in the sub—dollar greens fee but in the surreal presence of three solo golfers— “onesomes”—spaced out on a public course.

   2011, John Updike, Golf Dreams: Writings on Golf, page 50