The term 'slender rod' can be solved by the crossword solution 'SPINDLE, ' which is a seven-letter word. A SPINDLE is a thin, cylindrical rod that is used in various tools and machines. It is typically made of metal or wood and is used to hold, support, or rotate other parts. Spindles are commonly used in spinning wheels, lathes, and other machinery. They are also used in weaving looms and other textile equipment.