45 

Code for Goodnight. Usually finished with 143 and 1433 (meaning I love you and I love you too).

First Person: it's getting late, I'm getting tired.
Second Person: I'm going to go to bed, 45143.

First Person: 451433

45 by protohype02 November 26, 2016

.45 

Generally refers to a very commonplace handgun cartridge first developed for the 1911A1 Colt Autopistol, available in FMJ and JHP. A rather bulky round with a weight of roughly 11 grams, the .45 ACP is seen as the ultimate manstopper by American shooters. Though it is a sub-sonic round that uses relatively low-pressure charge, its sheer size can deliver enough energy to very literally stop a man in his tracks. On the flip side however, it does not have a substantial amount of piercing power. Other .45 cartridges include the .45 LC (for Colt Revolvers), .45 GAP (Glock Auto Pistol), and the .45-60 high-powered revolver load.

.45 by Anonymous August 10, 2003

45 

Referring to Donald Trump. The Daily Show with Trevor Noah calls him 45. In South Africa, 4 - 5 is slang for penis, according to Trevor. Its better than saying his name.

45 did this to Mexico today....

45 by HipWaldorf January 28, 2017

45 

.45 Caliber cartridge. Sometimes used to refer to the firearms that fire such cartridges.
11.4mm in diameter, the average .45 caliber bullet weighs half an ounce.
Though there are many arcane .45 caliber cartridges, the two most common are the .45ACP (automatic Colt Pistol) and the .45 Colt, which is an obsolete but popular round. The .45 Colt round is longer than the .45ACP round, and was designed by Colt to fit their Single Action revolver, which the US Army used during the last decades of the nineteenth century. The .45ACP round was designed to be used in the 1911 pistol, by John Moses Browning. The gun was adopted by the US Army a few years after its creation, and was used by the United States until it was replaced by the Beretta M9 (Military designation for the Beretta 92) during the 1980s. Because it was used during both World Wars, Korea and Vietnam, hundreds of thousands of 1911s were produced. The Colt 1911 is often referred to as a “Colt .45” or “Government .45.” The pitfalls of the .45ACP cartridge are the large size of the bullet, heavy recoil and poor ballistics. Because the bullet is nearly 2.5 millimeters greater in diameter than the 9mm cartridge, far fewer can fit in a gun’s magazine, and the gun must be larger in order to accommodate the bullet. The heavy felt recoil is also a problem, because rapid or continued fire is difficult to maintain on target. The ballistics of the .45 caliber cartridge are also disappointing, the round travels nearly 200 feet per second slower than a 9x19 (9mm) cartridge. The 1911 pistol is still popular, despite being nearly 100 years old in design. The firearm’s single action mechanism and low magazine capacity have been overcome by some firearm manufacturers, most notably Para-Ordinance, whose LDA trigger systems are amazing, and whose high magazine capacity frames have revitalized the 1911 pistol.

If I don't get ya money yo 'gone catch a foty-five!

45 by Rob April 14, 2004

45 

1) a firearm chambered for the .45 ACP cartridge (usually a large frame semi-automatic) or the ammunition for same.
2) phonograph record or player with 45 RPM spindle speed.
3) (archaic) a firearm chambered for the .45 Colt cartridge (commonly a single-action revolver, as seen in western movies)

45 by Aantgray February 13, 2003

45 

A back handed slap in the face using 4 fingers followed by an open handed 5 finger slap in the opposite direction.

Dude you're pissing me off! Shut up before I 45 ya!

45 by Sambiase March 29, 2015

45 

1) A Crazy Person (Derived from police code)

2) A Hooligan

Requesting backup, there is a 45 at the playground threatening people

Look at that 45 vapeing over there

45 by Szechuan October 13, 2017