Initialism of jet propellant 4., a wide-cut fuel designed by the U.S. military and formerly used in colder environments.

plural of 4-H'er

A participant in 4-H.

In the United States, a youth organization administered by the Cooperative Extension System of the United States Department of Agriculture with the mission of "engaging youth to reach their fullest potential while advancing the field of youth development."

(CB slang) affirmative. / Message received, understood, acknowledged

plural of 4-polytope

(geometry) A four-dimensional polytope.

(biblical) A book of the Old Testament of Bible, and of the Tanakh.

(physics) The normal isotope of helium, ⁴₂He, that has two neutrons

plural of 0-4-0+0-4-0