spiro-1Pronunciation: /ˈspʌɪrəʊ/Definition of spiro- combining form 1spiral; in a spiral:spirochaete 2 Chemistry denoting a molecule with two rings with one atom common to both:spironolactoneOrigin:from Latin spira, Greek speira 'a coil'spiro- in other Oxford dictionaries Definition of spiro- in the US English dictionary