(aviation) Initialism of jet propellant 1. (a highly refined kerosene; a type of jet fuel)

(video games) An item that grants the player an extra life in the game, staving off game over by one more try. / (video games) In a game with multiple players, an indicator or identifier of player 1.

The Garand semiautomatic rifle, also named the United States Rifle, Caliber .30, M1.

(initialism) Herpes simplex virus type 1, Human herpesvirus 1 in genus Simplexvirus.

(politics) A group of six world powers (China, France, Russia, the United Kingdom, and the United States, plus Germany) which joined the diplomatic efforts with Iran with regard to its nuclear program.

plural of 1-up

A laplet computer.

(medicine) Once per day, used for prescription directions.

Abbreviation of 1 Corinthians.

Initialism of one-dimensional.