prebreathe

pre·breathe

vt \(ˈ)prē-ˈbrēth\

pre·breathedpre·breath·ing

Definition of PREBREATHE

: to breathe (pure oxygen) to purge the blood of nitrogen content in preparation for an activity (as a space walk) that involves exposure to a significant change in pressure which might otherwise cause decompression sickness

—pre·breath·ing \-iŋ\ noun