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)

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!

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

by Szechuan October 13, 2017

45

.45 is the caliber, in inches, not mm. a 45mm gun is fucking huge.

Whoever thought a .45 is a 45mm is a moron.

by Anonymous February 11, 2003

45

A beer called Colt 45 & can be ordered at many convience stores

Hey Jamall grab me a 6 of 45!

by Damnit Janit June 17, 2007

45

To double cross.

She was 45ed by her own brother and lost her clearance and her house.

by LanceHN August 12, 2019

45

A phonograph record played at 45 RPM. It was about 8 inches across and had a very large central hole. It played a single song.

Peggy Sue has a whole box of Elvis 45s.

by Cap'n Bullmoose April 23, 2005