(1):

(n.) An element of speech entirely destitute of vocality, or produced by the breath alone; a nonvocal or surd consonant; a breathing.

(2):

(a.) Characterized by atony, or want of vital energy; as, an atonic disease.

(3):

(a.) Unaccented; as, an atonic syllable.

(4):

(a.) Destitute of tone vocality; surd.

(5):

(n.) A word that has no accent.

(6):

(n.) A remedy capable of allaying organic excitement or irritation.