In algebraic geometry, there are two slightly different definitions of an fpqc morphism, both variations of faithfully flat morphisms.
Sometimes an fpqc morphism means one that is faithfully flat and quasi-compact.
This is where the abbreviation fpqc comes from: fpqc stands for the French phrase "fidèlement plat et quasi-compact", meaning "faithfully flat and quasi-compact".
However it is more common to define an fpqc morphism
of schemes to be a faithfully flat morphism that satisfies the following equivalent conditions: Examples: An open faithfully flat morphism is fpqc.