Adjectives

(s)bland, flat, flavorless, flavourless, insipid, savorless, savourless, vapidlacking taste or flavor or tang“a bland diet”, “insipid hospital food”, “flavorless supermarket tomatoes”, “vapid beer”, “vapid tea”
(s)insipid, jejunelacking interest or significance or impact“an insipid personality”, “jejune novel”