a. 1. Incapable of being reversed or turned about or back; incapable of being made to run backward; as, an irreversible engine; an irreversible process; an irreversible reaction. [ 1913 Webster +PJC ]

2. Incapable of being reversed, recalled, repealed, or annulled; as, an irreversible sentence or decree. [ 1913 Webster ]

This rejection of the Jews, as it is not universal, so neither is it final and irreversible. Jortin.

Syn. -- Irrevocable; irrepealable; unchangeable. [ 1913 Webster ]

n. The state or quality of being irreversible. [ 1913 Webster ]

. (Mach.) A steering gear, esp. for an automobile, not affected by the road wheels, as when they strike an obstacle side ways, but easily controlled by the hand wheel or steering lever. [ Webster 1913 Suppl. ]

adj. Not reversible or capable of having either side out; -- used mostly of clothing. Opposite of reversible.
Syn. -- one-sided. [ WordNet 1.5 ]

a. [ Cf. F. réversible revertible, reversionary. ] 1. Capable of being reversed; as, a chair or seat having a reversible back; a reversible judgment or sentence. [ 1913 Webster ]

2. Hence, having a pattern or finished surface on both sides, so that either may be used; -- said of fabrics. [ 1913 Webster ]

Reversible lock, a lock that may be applied to a door opening in either direction, or hinged to either jamb. --
Reversible process. See under Process. [ 1913 Webster ]