A fault or malfunction.

The quantity or amount by which anything falls short.

(mathematics) A part by which a figure or quantity is wanting or deficient.

(intransitive) To abandon or turn against; to cease or change one's loyalty, especially from a military organisation or political party.

(military) To desert one's army, to flee from combat.

(military) To join the enemy army.

(law) To flee one's country and seek asylum.