The term CANDLE THREAD can be broken down into two crossword solutions: WICK (4 letters). A WICK is a thin piece of material that is used to draw fuel up from a container and into a flame. It is typically made of braided cotton, but can also be made of other materials such as paper, hemp, or linen. The WICK is lit, and the heat from the flame causes the fuel to evaporate and burn. The candle thread is the part of the WICK that is visible above the wax of the candle.