Sentence:  The wall facing the ocean was all glass and could be folded back in sections, <WSD>bifolds</WSD>, to almost completely have no wall at all, just a fulllength balcony and the ocean. 
Meaning of the word marked with <WSD> tags:  A door, window, shutter, or divider consisting of two equal panels hinged together so that it opens by folding the panels against each other.