noun

• A twist or fold.
• Any of the folds on the surface of the brain.
• The shape of something rotating; a vortex.
• The state or condition of being convoluted.
• (mathematics, functional analysis) A mathematical operation on two functions that produces a third that expresses how the shape of one is modified by the other; the integral of the product of the two functions after one is reflected about the y-axis and shifted along the x-axis.
• (computing) A function which maps a tuple of sequences into a sequence of tuples.
• One 360° turn in a spring or similar helix.