Something that dilutes or makes a substance weaker, or a person who dilutes substances.
From Latin 'diluere' with the agent suffix '-er.' One who or that which performs the action of diluting or weakening.
The concept of the 'diluer' was especially important in medieval medicine—apothecaries would dilute expensive herbal mixtures to stretch them further, making the word a euphemism for 'person making medicines cheaper!'
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