'microvessel' originates as a compound in modern English from the prefix 'micro-' and the noun 'vessel'. 'Micro-' comes from Greek 'mikros' meaning 'small' (via New Latin/Modern formation), and 'vessel' comes from Old French 'vessel' (from Latin 'vās', 'vasis') meaning 'container' or 'vessel'.

'vessel' entered English from Old French 'vessel' (also Middle English 'vessel(e)') derived from Latin 'vās'/'vasum'. The combining form 'micro-' was adopted from Greek 'mikros' into scientific/technical vocabulary in New Latin and then into English, producing compounds such as 'microvessel' in modern medical usage.

Initially the elements meant 'small' and 'container/vessel'; in medical usage the compound came to mean specifically a 'very small blood vessel' rather than a small container.