n. An enlarged growth on a tree formed in response to damage or parasite. Sometimes called just a gall.
the GNU version of the Collaborative International Dictionary of English
n. A more or less round gall resembling a nut, esp. one of those produced on the oak and used in the arts. See gall, gallnut.
The Century Dictionary and Cyclopedia
n. An excrescence, chiefly of the oak. See gall, 1.
Word Usage
"After completion of laconic epistolary compositions she abandoned the implement of calligraphy in the encaustic pigment, exposed to the corrosive action of copperas, green vitriol and nutgall."