The term 'sway to and fro' can be represented by two crossword solutions: ROCK (4 letters) and WAVER (5 letters). The term 'sway to and fro' is a phrase that describes a back-and-forth movement, often used to describe the movement of a boat in the water or a person dancing. The word 'ROCK' can refer to the act of swaying back and forth, as well as the noun form of a large stone. The word 'WAVER' is a verb that means to move unsteadily or to fluctuate between two opinions.