'ectasia' originates from Greek, specifically the word 'ektasis', where 'ek-' meant 'out' and 'tasis' (from 'tassein'/'teinein' roots) meant 'a stretching' or 'extension'.

'ektasis' passed into medical Latin/Neo-Latin as 'ectasia' and was adopted into English medical usage with little change to form, retaining the specialized sense.

Initially, it meant 'extension' or 'stretching out' in Greek, but over time it evolved into the more specific medical meaning of 'pathological dilation or widening' of anatomical tubes or vessels.