3. Any small aperture or vent for air or other fluid.
SPIRACULAR
Spi*rac"u*lar, a.
Defn: Of or pertaining to a spiracle.
SPIRAEA
Spi*ræ"a, n. Etym: [L., fr. Gr. (Bot.)
Defn: A genus of shrubs or perennial herbs including the meadowsweet and the hardhack.
SPIRAEIC
Spi*ræ"ic, a. (Chem.)
Defn: Of, pertaining to, or derived from, the meadowsweet (Spiræa); formerly, designating an acid which is now called salicylic acid.
SPIRAL
Spi"ral, a. Etym: [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.