tannic \tan"nic\, a.
   of or pertaining to tan; derived from, or resembling, tan;
   as, tannic acid.
   1913 webster

   tannic acid. chem.
   a an acid obtained from nutgalls as a yellow amorphous
       substance, c14h10o9, having an astringent taste, and
       forming with ferric salts a bluish-black compound, which
       is the basis of common ink. called also tannin, and
       gallotannic acid.
   b by extension, any one of a series of astringent
       substances resembling tannin proper, widely diffused
       through the vegetable kingdom, as in oak bark, willow,
       catechu, tea, coffee, etc.
       1913 webster
see also:
tannic acid c14h10o9 tannin gallotannic acid