IPA: //ʌnˈfoʊldər//
KK: /ʌnˈfoʊldər/
A person or thing that opens or reveals something that was previously folded or hidden.
The unfolder carefully opened the map to show the hidden trails.
Unfolder → It is formed from "un-" (meaning not or opposite of) and "folder" (from Old English "foldian", meaning to fold). The word "unfolder" means one who does not fold or opens something that is folded.
Think of 'not folding' ('un-') something that is 'folded' ('folder') — that's why unfolder means to open or spread out.