spiral

Concise Oxford English Dictionary © 2008 Oxford University Press:
spiral/ˈspʌɪrəl/

▶adjective winding in a continuous and gradually widening (or tightening) curve around a central point or axis.

■ winding in a continuous curve of constant diameter about a central axis, as though along a cylinder; helical.

■ Astronomy denoting galaxies in which the stars and gas clouds are concentrated mainly in spiral arms.

▶noun

• 1 a spiral curve, shape, or pattern.

• 2 a progressive rise or fall of prices, wages, etc., each responding to an upward or downward stimulus provided by a previous one.

  ■ a process of progressive deterioration.

▶verb (spirals, spiralling, spiralled; US spirals, spiraling, spiraled)

• 1 take or cause to follow a spiral course.

• 2 show a continuous and dramatic increase.

  ■ (spiral down/downward) decrease continuously.

– derivatives
spirally adverb.

– origin C16: from med. L. spiralis, from L. spira (see spire2).