<p><strong>noun</strong></p><ul><li>any cylindrical piece or device on which something is wound.</li><li>a small cylindrical piece of wood or other material on which yarn is wound in spinning, for use in weaving; a bobbin.</li><li>a small cylinder of wood or other material on which thread, wire, or tape is wound, typically expanded or with a rim at each end and having a hole lengthwise through the center.</li><li>the material or quantity of material wound on such a device.</li><li>the cylindrical drum in a reel that bears the line (Angling).</li></ul><p><strong>verb</strong></p><ul><li>(used with object) to wind on a spool.</li><li>to unwind from a spool (usually followed by off or out).</li><li>(Computers) to operate (an input/output device) by using buffers in main and secondary storage.</li><li>(used without object) to wind.</li><li>to unwind.</li></ul>