'To stand on the defensive' definitions:

Definition of 'To stand on the defensive'

From: GCIDE

Defensive \De*fen"sive\, n. That which defends; a safeguard. [1913 Webster]
Wars preventive, upon just fears, are true defensives. --Bacon. [1913 Webster]
To be on the defensive, To stand on the defensive, to be or stand in a state or posture of defense or resistance, in opposition to aggression or attack. [1913 Webster]