  We report electrical transport measurements on CaMn$_{2}$Bi$_{2}$ single
crystals under applied pressure. At ambient pressure and high temperatures,
CaMn$_{2}$Bi$_{2}$ behaves as a single-band semimetal hosting N\'{e}el order at
$T_{N}=150$~K. At low temperatures, multi-band behavior emerges along with an
activated behavior typical of degenerate semiconductors. The activation gap is
estimated to be $\Delta \sim 20$~K. Applied pressure not only favors the
antiferromagnetic order at a rate of 0.40(2)~K/kbar, but also enhances the
activation gap at $20$~kbar by about $70$~\%. This gap enhancement is typical
of correlated narrow-gap semiconductors such as FeSi and
Ce$_{3}$Bi$_{4}$Pt$_{3}$, and places CaMn$_{2}$Bi$_{2}$ as a Mn-based
hybridization-gap semiconductor candidate. \textit{Ab initio} calculations
based on the density functional theory are shown to be insufficient to describe
the ground state of CaMn$_{2}$Bi$_{2}$.
