Dubbelvouwen

Dutch

• dubbelvouwen [dubbelgevouwen, dubbelgevouwd, vouwde dubbel, vouw dubbel, vouw het dubbel, etc.]

English

• fold double
• fold in two (IATE)
• fold in half
• double (up)
• bend double
• bend in two
• middle (het zeil dubbelvouwen = middle the sail)
• [TEX.] double, fold

Meaning of ‘to fold’

fold: 
Bend (something flexible and relatively flat) over on itself so that one part of it covers another

Synonyms: double, double over, double up, crease, turn under, turn up, turn over, bend, overlap;
tuck, gather, pleat, crimp, bunch 
(Oxforddictionaries.com)