4F
# 4F

4F or 4-F may refer to:

* 4F (company), a Polish sportswear company
* 4-F classification in the U.S. Selective Service System, identifying a person as unfit for military service
* 4F correlator, in Fourier optics
* The 4f electron shell
* Section 4(f) of the United States DOT act of 1966, which regulates acquiring park and historic properties for transportation use.
* 4F case, a 4 February 2006 controversial criminal case in Barcelona
* Flottille 4F a French naval aviation squadron
* LMS Fowler Class 4F, a class of 0-6-0 steam locomotive
* February 1992 Venezuelan coup d'état attempt, known in Venezuela as "4F".
