vap·id

offering nothing that is stimulating or challenging.

synonyms: insipid, uninspired, colorless, uninteresting, feeble, flat, dead, dull, boring, tedious, tired, unexciting, uninspiring, unimaginative, lifeless, zestless, spiritless, sterile, anemic, tame, bloodless, jejune, vacuous, bland, stale, trite, pallid, wishy-washy, watery, tasteless, milk-and-water, flavorless