1) Oak bark tannin 
• (a.) Pertaining to, or designating, a tannic acid found in oak bark and extracted as a yellowish brown amorphous substance.
Quer`ci·tan'nic adjective [ Latin quercus an oak + English tannic .] (Chemistry) Pertaining to, or designating, a tannic acid found in oak bark and extracted as a yellowish brown amorphous substance. 
quercitannic Referring to, or designating, a tannic acid found in oak bark and extracted as a yellowish brown amorphous substance.