Synonyms for Vapid (same or very similar meaning)
WordNet sense 1 (lacking taste or flavor or tang):
bland, flat, flavorless, insipid, flavourless, savorless, savourlessWordNet sense 2 (lacking flavor):
tastelessWordNet sense 3 (not stimulating):
unexciting, unstimulatingFrom the ODE community, based on WordNetadd/edit