  Very-high-energy (VHE; $>$ 100 GeV) gamma-ray emission from the blazar RGB
J2243+203 was discovered with the VERITAS Cherenkov telescope array, during the
period between 21 and 24 December 2014. The VERITAS energy spectrum from this
source can be fit by a power law with a photon index of $4.6 \pm 0.5$, and a
flux normalization at 0.15 TeV of $(6.3 \pm 1.1) \times 10^{-10} ~
\textrm{cm}^{-2} \textrm{s}^{-1} \textrm{TeV}^{-1}$. The integrated
\textit{Fermi}-LAT flux from 1 GeV to 100 GeV during the VERITAS detection is
$(4.1 \pm 0.8) \times 10^{\textrm{-8}}
~\textrm{cm}^{\textrm{-2}}\textrm{s}^{\textrm{-1}}$, which is an order of
magnitude larger than the four-year-averaged flux in the same energy range
reported in the 3FGL catalog, ($4.0 \pm 0.1 \times 10^{\textrm{-9}} ~
\textrm{cm}^{\textrm{-2}}\textrm{s}^{\textrm{-1}}$). The detection with VERITAS
triggered observations in the X-ray band with the \textit{Swift}-XRT. However,
due to scheduling constraints \textit{Swift}-XRT observations were performed 67
hours after the VERITAS detection, not simultaneous with the VERITAS
observations. The observed X-ray energy spectrum between 2 keV and 10 keV can
be fitted with a power-law with a spectral index of $2.7 \pm 0.2$, and the
integrated photon flux in the same energy band is $(3.6 \pm 0.6) \times
10^{-13} ~\textrm{cm}^{-2} \textrm{s}^{-1}$. EBL model-dependent upper limits
of the blazar redshift have been derived. Depending on the EBL model used, the
upper limit varies in the range from z $<~0.9$ to z $<~1.1$.
