any of the various theories or doctrines or philosophical systems that attempt to explain the phenomena of the universe in terms of some immanent force or energy
the time required for something to fall to half its initial value (in particular, the time for half the atoms in a radioactive substance to disintegrate)
appearing dead; not breathing or having no perceptible pulse; "an inanimate body"; "pulseless and dead"
not breathing or able to breathe except with difficulty; "breathless at thought of what I had done"; "breathless from running"; "followed the match with breathless interest"
tending to cause suspension of regular breathing; "a breathless flight"; "breathtaking adventure"