had been diluting

• past perfect progressive

  past perfect progressive

  Used to describe an action that was ongoing continuously in the past up until another past event interrupted it.

  of dilute.
  dilute

  verb (used with object)

  to make (a liquid) thinner or weaker by the addition of water or the like.

Related Words

• adulterate
• alter
• decrease
• diminish
• lessen
• mitigate
• modify
• reduce
• temper
• water down