What is another word for high-altitude?
Pronunciation: [hˈa͡ɪˈaltɪtjˌuːd] (IPA) 
High-altitude can be replaced with several synonyms that describe the altitude or elevation of a location or an object. Proximate words that can replace high-altitude include elevated, lofty, cliffhanging, and sky-high. High-altitude could also be replaced by phrases such as extreme heights, mountainous regions, high-altitude environment, or up in the clouds. Other synonyms for high-altitude include sheer heights, towering heights, and elevated terrain. Whether we are referring to a location, an aircraft, or an athlete's training, there are multiple synonyms for high-altitude that accurately convey the same meaning.
