Definition of "nutgall" [nut•gall]

• A nutlike swelling produced on an oak or other tree by certain parasitic wasps. Also called gallnut. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The direct antidote is a solution of nutgall or oak bark."
• "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."
• "But the vegetable substance in which the gallic acid most abounds is _nutgall_, a kind of excrescence that grows on oaks, and from which the acid is commonly obtained for its various purposes."