Other forms: unfolding, unfolded, unfolds
To unfold something is to open it out flat. The map spread across the car bonnet, the deckchair opened on the grass, the letter that has been folded into three and now lies open on the table.
The larger use is about time. Events unfold: they develop step by step while you watch, and the drama unfolds, the story unfolds, a crisis unfolds on the news. In that sense nothing is being opened by anybody — the thing unfolds by itself, with no object after it. A bird unfolds its wings, a plan unfolds, an argument unfolds. The opposite is fold, or fold up, and the picture under both senses is the same: something closed and layered that opens into its full shape.
1verbunfoldTo open something that was folded and spread it out flat.
“She unfolded the map on the bonnet and traced the road with her finger.”
synonyms: open out, spread out
2verbdevelopOf events or a story: to develop and become clear over time.
“The scandal unfolded over three weeks of front pages.”
3verbrevealTo reveal or explain something bit by bit.
“He unfolded his plan to us slowly, keeping the cost until last.”
Unfold is as old as English gets. Old English had unfealdan, to unfold, made of un- and fold, and it came through Middle English as unfolden with barely a change. The un- here undoes an action rather than denying a quality — the same un- as in untie and unlock.
Old English
unfealdan — to unfold
Middle English
unfolden
English, today
unfold
From Middle English unfolden, from Old English unfealdan (“to unfold”), equivalent to un- + fold.
Etymology from Wiktionary, CC BY-SA