21-letter words containing s, o, a, k
- uk overseas territory — any of the territories that are governed by the UK but lie outside the British Isles; many were formerly British crown colonies: includes Bermuda, Falkland Islands, and Montserrat
- universal disk format — (storage, standard) (UDF) A CD-ROM file system standard that is required for DVD ROMs. UDF is the OSTA's replacement for the ISO 9660 file system used on CD-ROMs, but will be mostly used on DVD. DVD multimedia disks use UDF to contain MPEG audio and video streams. To read DVDs you need a DVD drive, the kernel driver for the drive, MPEG video support, and a UDF driver. DVDs containing both UDF filesystems and ISO 9660 filesystems can be read without UDF support. UDF can also be used by CD-R and CD-RW recorders in packet writing mode.
- venus's flower basket — a glass sponge of the genus Euplectella, inhabiting deep waters off the Philippines and Japan, having a cylindrical skeleton formed of an intricate latticework of siliceous spicules.
- venus's looking glass — a purple-flowered campanulaceous plant, Legousia hybrida, of Europe, W Asia, and N Africa
- vladivostok agreement — a preliminary arms control accord concluded by Soviet leader Leonid Brezhnev and U.S. President Gerald Ford in Vladivostok, U.S.S.R., in December 1974.
- workers' compensation — a government-sponsored insurance system, funded by contributions from employers, for compensating employees for injury or occupational disease suffered in connection with their employment