What is "litui"

Lituus \Lit"u*us\, n.; pl. Litui. [L.]

1. (Rom. Antig.)

   1. A curved staff used by the augurs in quartering the heavens.

   2. An instrument of martial music; a kind of trumpet of a somewhat curved form and shrill note.

2. (Math.) A spiral whose polar equation is r^ 2[theta] = 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.

n. (plural of lituus English)