Spi*rac"u*lar (?), a. Of or pertaining to a spiracle.
Spi*ræ"a (?), n. [L., fr. Gr. &?;&?;&?;, fr. &?;&?;&?; a coil.] (Bot.)
A genus of shrubs or perennial herbs including the meadowsweet and the
hardhack.
Spi*ræ"ic (?), a. (Chem.) Of, pertaining to, or derived from, the
meadowsweet (Spiræa); formerly, designating an acid which is now called
salicylic acid.
Spi"ral (?), a. [Cf. F. spiral. See Spire a winding line.] 1. Winding
or circling round a center or pole and gradually receding from it; as,
the spiral curve of a watch spring.
2. Winding round a cylinder or imaginary axis, and at the same time
rising or advancing forward; winding like the thread of a screw;
helical.