Lockable

[f. LOCK v.¹ + -ABLE.] That can be locked.

1893.  Field, 4 March, 335/1. Lockable hatches.

1898.  J. L. Long, in Century Mag., Jan., 375/1. Some clever Japanese artisans then made the paper walls of the pretty house eye-proof, and, with their own adaptations of American hardware, the openings cunningly lockable.