LITUUS
Etymology
Noun
lituus (plural litui)
A military trumpet.
(geometry) A curve with polar equation , where a is a constant.
Source: Wiktionary
Lit"u*us, n.; pl. Litui. Etym: [L.]
1. (Rom. Antig.)
(a) A curved staff used by the augurs in quartering the heavens.
(b) An instrument of martial music; a kind of trumpet of a somewhat
curved form and shrill note.
2. (Math.)
Definition: A spiral whose polar equation is r2th = a; that is, a curve the
square of whose radius vector varies inversely as the angle which the
radius vector makes with a given line.
Source: Webster’s Unabridged Dictionary 1913 Edition