'calculus-forming' originates from Modern English, formed by compounding the noun 'calculus' and the present-participle 'forming'. 'Calculus' comes from Latin 'calculus' meaning 'small pebble', and 'forming' derives from Latin 'formare' via Old French/Latin meaning 'to shape or make'.

'calculus' entered English from Late Latin/Medieval Latin 'calculus' (a small stone used for counting) and came to be used for natural stones (such as kidney stones and dental tartar). 'Forming' is the present participle of 'form', which comes from Latin 'formare' through Old French and Middle English; the compound 'calculus-forming' is a straightforward Modern English coinage that joins the noun and participle.

Initially, 'calculus' meant a 'small pebble' used for counting; over time it evolved to mean a 'stone' in the body (e.g., kidney stone or dental tartar). The compound now specifically denotes something that causes or promotes such stone formation.