[shim] 
noun, verb, shimmed, shim⋅ming.| 1. | a thin slip or wedge of metal, wood, etc., for driving into crevices, as between machine parts to compensate for wear, or beneath bedplates, large stones, etc., to level them. |
| 2. | to fill out or bring to a level by inserting a shim or shims. |
| shim (shĭm) n. A thin, often tapered piece of material, such as wood, stone, or metal, used to fill gaps, make something level, or adjust something to fit properly. tr.v. shimmed, shim·ming, shims To fill in, level, or adjust by using shims or a shim. [Origin unknown.] |
shim jargon, memory management
A small piece of data inserted in order to achieve a desired memory alignment or other addressing property.
For example, the PDP-11 Unix linker, in split I&D (instructions and data) mode, inserts a two-byte shim at location 0 in data space so that no data object will have an address of 0 (and be confused with the C null pointer).
See also loose bytes.
[The Jargon File]
(1994-12-21)