||Lit"u*us (?), n.; pl. Litui (#). [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.) A spiral whose polar equation is r²θ = 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.

• A military trumpet.
       Quotations
       *1786: Fig. 3. A Roman Lituus, or military trumpet, such as is mentioned by Horace in his first ode. — Francis Grose, A Treatise on Ancient Armour and Weapons, page vi.
  
• (geometry) A curve with polar equation r^2 \theta = a^2, where a is a constant.
  
  Latin
• a military trumpet
  
• a curved staff