We report high-resolution results from the well-known ''Shockley''-type surface state localized around the Ȳ point of the Cu͑110͒ surface Brillouin zone. Along ⌫Y the effective mass is m*/mϭ0.26Ϯ0.03 and the bottom of the dispersion parabola at Ȳ shifts linearly with sample temperature T as E 0 ϭϪ(510Ϯ15)meV ϩ(0.26Ϯ0.02 meV/K)T. We have also analyzed the photoemission linewidth ⌫ h of this surface state. Our analysis results in an upper limit for the imaginary part of the self-energy Im ⌺ϭ⌫ h /2р(16Ϯ3)meV, which corresponds to a photohole lifetime у(21Ϯ5)fs at Ȳ and T→0. On the basis of recent calculations of ⌫ h for Cu͑111͒ at ⌫ ͓Chulkov et al., Surf. Sci. ͑to be published͔͒ we interpret ⌫ h of Cu͑110͒ at Ȳ by inelastic hole-electron interactions, with about 50% contribution each from surface band ͑in-plane͒ and from threedimensional ͑coupling to substrate͒ decay channels. Finally we discuss the contribution of the Ȳ surface state to the surface optical properties as observed in both second harmonic generation and ͑one-photon͒ reflection anisotropy spectroscopy from Cu͑110͒.