ppl. a. (UN-1 8. Cf. Da. utappet.)
In frequent use (esp. fig.) from c. 1890.
[1775. Ash.]
1779. Warner, in Jesse, Selwyn & Contemp. (1844), IV. 254. An untapped barrel of ale.
1863. Bates, Nat. Amazons, I. 143. Untapped [india-rubber] trees still growing in the wilds.
1889. C. Edwardes, Sardinia, 164. What a fund of mirth lay untapped within him!