subordinating conjunction

/S AH0 B AO1 R D AH0 N EY0 T IH0 NG K AH0 N JH AH1 NG K SH AH0 N/
noun
  1. 1

    (grammar) A word that appears at the beginning of a subordinate clause and establishes its nature.

Source: https://en.wiktionary.org/wiki/subordinating%20conjunction