accordion-fold

[ uh-kawr-dee-uh n-fohld ]
/ əˈkɔr di ənˌfoʊld /

verb (used with object)

to fold into pleats resembling the bellows of an accordion: to make a fan by accordion-folding a sheet of paper.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019