noun which may take the genitive case particle 'no', noun
greatest in history; largest ever; biggest on record
Used attributively before a noun to describe something as the greatest, largest, or most significant in recorded history. Often appears in news headlines and formal contexts.
This is the greatest project in history.
The largest earthquake in history struck the region.
過去最大 means 'largest to date' or 'largest in the past', focusing on a record up to the present, while 史上最大 emphasizes the entire span of recorded history.
Compound of 史上 (shijō, 'in history') and 最大 (saidai, 'largest, greatest'). The exact historical derivation is straightforward; the word is a modern Sino-Japanese compound.