unroll

Unroll is a verb meaning to unwind or spread out something that has been rolled up. It can describe physical objects such as carpets, maps, posters, scrolls, films, or sleeping bags, as well as actions that reveal or disclose what was compacted. The noun form is rare; the verb is used in both concrete and figurative contexts.

In practical use, unrolling involves laying the object on a flat surface and gradually drawing it outward while smoothing folds and creases. Care is taken to avoid overstretching delicate materials. Unrolling can reveal content or assembly details hidden when the item was rolled.

In computing, unrolling refers to loop unrolling, an optimization that expands the loop body to reduce the overhead of branching and iteration. This can improve instruction throughput and cache behavior on some architectures, but increases code size and may worsen register pressure or speculative execution effects, so it is often applied selectively or automated by compilers.

In geometry and manufacturing, unrolling describes transforming a curved surface into a flat development. A cylinder unrolled becomes a rectangle whose width equals the circumference; a cone becomes a sector of a circle. These developments are used for planning fabrication, patterning, and technical drawing.

Etymology: the word merges the negating prefix un- with roll, from Old English words related to turning or winding.