Gerund; uncountable noun denoting the act or process of making something less dense.
Переводы
The rarefying of the atmosphere at high altitudes affects breathing.
Разрежение атмосферы на больших высотах влияет на дыхание.
Определения
The act or process of making or becoming less dense or more rare. The rarefying of the atmosphere at high altitudes affects breathing.