What is Breath?

Legal Definition
Med. juris. The air expelled from the chest at each expiration.

2. Breathing, though a usual sign of life, is not conclusive that a child was wholly born alive, as breathing may take place before the whole delivery of the mother is complete. 5 Carr. & Payn, 329; S. C. 24 E. C. L. R. 344. Vide Birth; Life; Infanticide.
-- Bouviers Law Dictionary
Legal Definition
In medical jurisprudence. The air expelled from the lungs' at each expiration.
-- Black's Law Dictionary