wash out

1.  Remove or be removed by washing; also, cause to fade by laundering. For example, Give it to me; I'll wash out that stain, or The bleach has really washed out that bright print. [Mid-1700s]
2.  Wear away or be worn away by the flow of water, as in The river rose and washed out the dam, or The road has completely washed out. [Mid-1700s]
3.  Deplete or be depleted of energy, as in Working on her feet all day just washed her out, or I just washed out after that long tennis match. [Mid-1800s]
4.  Eliminate or be eliminated as unsatisfactory, as in He washed out of medical school after just one year, or After only two months as chairman I washed out. [Colloquial; early 1900s]
5.  Cancel owing to bad weather, as in The picnic was washed out. [Colloquial; early 1900s] Also see washed out.

The verb has 7 meanings:

Meaning #1: prevent or interrupt due to rain
  Synonym: rain out

Meaning #2: wash free from unwanted substances, such as dirt

Meaning #3: make useless by the force of water

Meaning #4: remove by the application of water or other liquid and soap or some other cleaning agent
  Synonyms: wash, wash off, wash away

Meaning #5: deplete of strength or vitality

Meaning #6: drain off the color in the course of laundering

Meaning #7: lose color in the process of being washed