Something that conduces or contributes toward a result; that which helps promote or facilitate.
From 'conduce' + the suffix '-er' (forming agent nouns). This is a very rare word, mostly appearing in historical texts.
Conducer is an obscure agent noun that would mean 'one who or that which conduces'—it's the kind of word that linguists find in dusty old texts but would rarely be useful in modern English, where we'd say 'facilitator' or 'contributor' instead.
Complete word intelligence in one call. Free tier — 50 lookups/day.