Entry 3 senses · 2 variants Webster, 1913 Diluent · Dil·u·ent · IPA /ˈdɪljuənt/ a. n. 01 a. Diluting; making thinner or weaker by admixture, esp. of water. 1. Diluting; making thinner or weaker by admixture, esp. of water. 02 n. That which dilutes. 1. That which dilutes. 2. An agent used for effecting dilution of the blood; a weak drink.(Med.) “There is no real diluent but water.” — Arbuthnot.