spir(o)-²

The breath; breathing.

Latin spirare, to breathe.

A spirograph is an instrument for recording breathing movements, as is a spirometer, both of which record their results on spirograms; the process of investigation is called spirometry (Spirograph is also the name given to a toy for drawing intricate curved patterns, from spiro‑¹.) In zoology, a spiracle is an external respiratory opening, for example on an insect.