1. Surface Mount Device (SMD): An electronic component that mounts on the surface of a printed circuit board (as opposed to "through-hole" components which have pins that are inserted into holes). SMDs typically allow more components per square centimeter of PC board, but their scale is such that hand assembly and prototyping may be difficult.
2. Standard Military Drawing (SMD): A U.S. government program for standardized MIL-STD-883 product specifications, to simplify military procurement. Sponsored by the DSCC (Defense Supply Center, Columbus).