OTF

1. abbreviationinitialismnot comparableInitialism of out-the-front, telescoping, describing a knife or sword which extends and retracts through a hole in one end of the handle, rather than folding (or having a fixed blade).

   I've found it better to just give them an OTF knife than to argue.

   2017, Roger Eckstine, Shooter's Bible Guide to Knives: A Complete Guide to Fixed and Folding Blade Knives for Hunting, Survival, Personal Defense, and Everyday Carry, Simon and Schuster, →ISBN

   3 more examples

   He retracted the OTF blade into the hilt and walked away. Azrael's phone rang. He sighed and answered the call. “What?” “What the hell do you think you are doing?” “I took care of a small problem.”

   2014, Jesse C. Pacheco, Requiem of Assassins I: Assassination of the Raven, Strategic Book Publishing Rights Agency, →ISBN, page 146

   Frank never went anywhere without his OTF (out the front) gravity knife, issued to him by Uncle Sam […] He pushed the button forward to eject the blade from its olive-green hilt, and swung his arm around toward his [target].

   2014, Randy Eberle, Gemini, Ingramspark/CreateSpace Independent/Gutzmer Publishing, →ISBN, page 129

   Straight-line spring or end-line spring - with a blade that fires both in and out, which utilizes a unique mechanism that simultaneously compresses the spring and releases the blade on each up-and-down movement of the button on the knife. This is often referred to as an “out the front” or OTF.

   [2015, Evan F. Nappen, Knife Laws of the U.S.: Loopholes, Pitfalls & Secrets, F+W Media, Inc., →ISBN

plural OTFs

1. abbreviationinitialismInitialism of orbital test flight.

   Synonyms: OFT