STEEPEN
steepen
(verb) make steeper; “The landslides have steepened the mountain sides”
steepen
(verb) become steeper; “The mountain side has steepened”
Source: WordNet® 3.1
Etymology
Verb
steepen (third-person singular simple present steepens, present participle steepening, simple past and past participle steepened)
(transitive) To make steeper.
(intransitive) To become steeper.
• H. Miller
Anagrams
• ensteep
Source: Wiktionary
Steep"en, v. i. [imp. & p. p. Steepened; p. pr. & vb. n. Steepening.]
Definition: 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.
Source: Webster’s Unabridged Dictionary 1913 Edition