the indefinite boundary in the upper atmosphere beyond which the air is too thin for conventional aircraft to operate.
Origin of aeropause
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
the region of the upper atmosphere above which aircraft cannot fly
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012