It means that it is very skinny, skinny or thin. You can refer to a person, animal, plant (especially lianas or vines) and up to things (a wire).
Also cencello or rime. So say my Zamora ashore to spray ice accumulated on the branches of the trees in the cold days of winter. In the toughest winters the cenceno builds up days and days on the banks of the rivers like the Douro, caught in an icy mist.