'occluded' (from the verb 'occlude') originates from Latin, specifically the verb 'occludere', where the prefix 'oc-' (a variant of 'ob-') meant 'toward/against' and 'cludere' (from 'claudere') meant 'to shut'.

'occludere' produced Latin past participle 'occlusus'; the verb entered English scientific and technical usage via Medieval/Neo-Latin (and later modern Latin forms) and became the English 'occlude' with past participle 'occluded'.

Initially it meant 'to shut up or close' in Latin, and over time it retained that core sense; in modern English it is used both broadly for 'block/close' and in specialized senses (medical, dental, meteorological).