Wiktionary
lockfast
a. (context Scottish English) Fastened or secured with a lock.
Usage examples of "lockfast".
Every time Jennie Turnbull opened her lockfast place to add a coin, sometimes two, to the hoard which Tom knew nothing about, she wondered why she kept such a lot of old, sad things.
John Stewart, a warlock of Irvine, in 1618, "for his better preferring to the day of the assys, was put in one lockfast buith, .
There were impact-dispersing skullcaps for the clumsy, disposable looparound mouthpieces for the tongue gnashers, lockfast maxi-Pampers for the thrashing incontinent, and countless kinds of medication reminders that beeped and buzzed and chimed to remind the forgetful.