Plural of circulatory; things or systems related to circulation, though this word is rarely used in modern English.
From 'circulatory' (adjective describing systems of circulation) + the plural suffix '-ies'. This is an archaic or obsolete formation, as modern English prefers 'circulatory systems' rather than using the noun form plurally.
This word is virtually extinct in modern usage—it's a grammatical ghost, technically possible but so awkward that nobody actually says it. Finding it in old medical texts is like discovering a linguistic fossil.
Complete word intelligence in one call. Free tier — 50 lookups/day.