timberline

• timber line

 

From timber +‎ line.

• (US) IPA^(key): /ˈtɪmbɚˌlaɪn/

timberline (plural timberlines)

1. The height or limit beyond which trees do not grow in mountainous or Arctic regions.

   Synonym: tree line

   • 1915 April, Enos A. Mills, “Wild Mountain Sheep”, in The Rocky Mountain Wonderland, Houghton Mifflin, →LCCN, →OCLC, page 37:

     Most flocks in the Sierra and the Rocky Mountains live above the timber-line and at an altitude of twelve thousand feet.