The term 'threaten to fall' can be represented by the crossword solution 'TEETER, ' which is a six-letter word. TEETER means to sway unsteadily, as if about to fall, or to be in a precarious position. It is often used to describe someone who is in danger of losing their balance or falling. In this context, the term 'threaten to fall' implies that something is in a precarious position and could potentially fall or collapse.