Dilutant
Part of speech: noun
Definition: A diluting agent; a diluent.
Diluent
Part of speech: noun
Definition: That which dilutes.A solvent or other liquid preparation used to dilute a sample prior to testing.An agent used for effecting dilution of the blood; a weak drink.
Part of speech: adjective
Definition: Diluting; making thinner or weaker by admixture, especially of water.