at arm's length

1. At a distance, avoiding intimacy or familiarity, as in Bill hated seeing his colleagues outside the office, preferring to keep all of them at arm's length, or She was friendly only when he was safely at arm's length. Now often used with the verb keep, this term for distancing oneself from a person, organization, or issue originated as at arm's end but developed its current form by the mid-1600s.