Optical through NIR wavelength spectroscopy of SN 2014ab, extending from +54 d to 183 d (restframe days) past the first WISE detection. The numbers in the parentheses indicate the flux offset adopted for the spectra in the unit of 10⁻¹⁶ erg s⁻¹ cm⁻² Å⁻¹. The shaded wavelength regions indicate areas of strong telluric absorption. The last three spectra are not calibrated by photometry because of the lack in the photometric information.