When we think of the word "ducts," we often think of channels or passages used for transportation. Antonyms for "ducts" would include words that describe obstruction, blockage or the absence of a channel altogether. Words like clog, jam, and hinder all carry a negative connotation, suggesting that something is preventing the normal flow of movement. Conversely, words like free, unobstructed, and clear connote open paths and free passage. These antonyms remind us that while ducts are often necessary for the movement of certain substances or objects, they can also be impeded or blocked, leading to potential problems.