We explore the effective field theory of a vector ${X}^{\ensuremath{\mu}}$ that has St\"uckelberg mass. The absence gauge symmetry for implies Lorentz-invariant operators are constructed directly from ${X}^{\ensuremath{\mu}}$. Beyond kinetic and mass terms, allowed interactions at renormalizable level include ${X}_{\ensuremath{\mu}}{X}^{\ensuremath{\mu}}{H}^{\ifmmode\dagger\else\textdagger\fi{}...