D defs.my
Entry 1 sense Webster, 1913

Steepen

/(stēp"'n)/ · Steep·en · IPA
01 v. i. To become steep or steeper.
imp. & p. p. Steepened; p. pr. & vb. n. Steepening
  1. 1.
    To become steep or steeper.
    “As the way steepened . . . I could detect in the hollow of the hill some traces of the old path.” — H. Miller.