"In particle physics, preons are postulated "point-like" particles, conceived to be
subcomponents of quarks and leptons.[1] The word was coined by Jogesh Pati and Abdus Salam in 1974. Interest in preon models peaked in the 1980s but has slowed as the Standard Model of particle physics continues to describe the physics mostly successfully, and no direct experimental evidence for lepton and quark compositeness has been found, although in the hadronic sector there are some intriguing open questions and some effects considered as anomalies within the Standard Model. For example, four very important open questions are the proton spin puzzle, the EMC effect, the distributions of electric charges of the nucleons found by Hofstadter in 1956, and the ad hoc CKM matrix elements."
"A number of physicists have attempted to develop a theory of "pre-quarks" (from which the name preon derives) in an effort to justify theoretically the many parts of the Standard Model that are known only through experimental data."
"Other names which have been used for these proposed fundamental particles (or particles intermediate between the most fundamental particles and those observed in the Standard Model) include prequarks, subquarks, maons,[3] alphons, quinks, Rishons, tweedles, helons, haplons, and Y-particles.,[4] primons.[5] Preon is the leading name in the physics community."