Nutgall

Part of speech: noun

Definitions

1. A rounded swelling on oak trees formed when gall wasps lay eggs in the bark ; a tannin-rich material taken from these growths and used in making dyes and ink
2. A knobbly outgrowth on certain oaks produced by insect larvae ; a astringent substance harvested from these lumps for use in tanning and writing ink
3. The hard abnormal lump on an oak caused by a wasp's egg-laying ; a bitter, tannin-heavy product extracted from these oak swellings for dyeing and ink-making

Etymology: Nutgall is a compound of "nut" and "gall", and both parts carry their original senses into the word. A gall is a swelling or growth produced on an oak or other plant, usually after an insect has laid its eggs in the tissue. The growth forms around the larva, which feeds on the plant as it develops. The "nut" half refers to the rounded, hard shape of these growths, which look like small nuts hanging from the branches. Nutgalls were prized for their high tannin content. They were ground and steeped to make dyes and to produce iron-gall ink, the dark writing fluid used for centuries in European manuscripts and documents. The compound therefore names a plant growth whose main value lay in the chemistry of its tannins rather than in any resemblance to a true nut.

Synonyms: gallnut, oak apple