1) Dying 1) Losing validity 
• (a.) Breathing out air from the lungs; emitting fluid or volatile matter; exhaling; breathing the last breath; dying; ending; terminating. • (p. pr & vb. n.) of Expire • (a.) Pertaining to, or uttered at, the time of dying; as, expiring words; expiring groans.
Ex·pir'ing adjective 1. Breathing out air from the lungs; emitting fluid or volatile matter; exhaling; breathing the last breath; dying; ending; terminating. 2. Pertaining to, or uttered at, the time of dying; as, expiring words; expiring groans.