The story
From the convention of using "X" as a variable to stand for something unknown.
Etymology from Wiktionary, CC BY-SA 4.0.
X-disease
Today it means: Hyperkeratosis in cattle. Full definition →
Today it means: Hyperkeratosis in cattle. Full definition →
From the convention of using "X" as a variable to stand for something unknown.
Etymology from Wiktionary, CC BY-SA 4.0.