'guess-based' originates from Modern English, formed by combining the noun 'guess' and the past participle 'based'. 'guess' ultimately comes from Middle English 'gessen' influenced by Old Norse 'giska', where the root meant 'to take an approximate estimate', and 'base' comes from Latin 'basis' via Old French where it meant 'foundation'.

'guess' developed from Middle English 'gessen' (from Old Norse 'giska'), and 'base' came from Latin 'basis' through Old French; the compound 'guess-based' is a contemporary English formation that joins these elements to describe something founded on guesswork.

Initially the root elements referred to 'making an approximate estimate' and 'foundation'; over time the compound came to mean 'founded on conjecture or estimation' rather than on firm evidence.