single file

/S IH1 NG G AH0 L F AY1 L/
noun
  1. 1

    A line or queue one person wide.

    โ€œThey walked in a single file.โ€

adjective
  1. 1

    (of a line or queue) One person wide.

    โ€œThey walked in a single file line.โ€

adverb
  1. 1

    In a line or queue one person wide.

    โ€œThey walked single file.โ€

Source: https://en.wiktionary.org/wiki/single%20file