Douglas Harper's Etymology Dictionary
spiro-
word-forming element meaning "twisted, spiraled, whorled," from comb. form of Latin spira "a coil, twist," from Greek speira (see spiral (adj.)).
Wiktionary
spiro-
pre. 1 Forms terms related to spirals or helix 2 (context medicine English) Forms terms related to respiration 3 (context chemistry English) Forms terms related to spiro compounds