Why is the ninth month called September?
Old English spinel, properly "an instrument for spinning," from stem of spinnan (see spin (v.)), with intrusive -d-. Related to Old Saxon spinnila, Old Frisian spindel, Old High German spinnila, German Spindel. As a type of something slender, it is attested from 1570s.
spindle spin·dle (spĭn'dl)
A fusiform structure, usually composed of microtubules.
A network of protein fibers that forms in the cytoplasm of a cell during cell division. The spindle grows forth from the centrosomes and attaches to the chromosomes after the latter have been duplicated, and the nuclear membrane dissolves. Once attached, the spindle fibers contract, pulling the duplicate chromosomes apart to opposite poles of the dividing cell. See more at meiosis, mitosis.