flavourless

/F L EY1 V ER1 L AH0 S/
adjective
  1. 1

    Lacking taste or flavor; without seasoning, spice, or discernible qualities of taste.

  2. 2

    Flat; lacking character or definition.

  3. 3

    Without flavor.

Source: https://en.wiktionary.org/wiki/flavorless, https://en.wiktionary.org/wiki/flavourless