(intra-company) job transfer away from one's family; unaccompanied posting
来月から単身赴任する。
I'll be taking an unaccompanied posting starting next month.
彼は単身赴任を命じられた。
He was ordered to take an unaccompanied posting.
父は大阪に単身赴任しているそうだ。
I hear my father is on an unaccompanied posting in Osaka.