21-letter words containing s, a, d, i
- tsutsugamushi disease — scrub typhus.
- turn state's evidence — If someone who is accused of a crime turns state's evidence, they agree to give evidence in a law court against another person such as a former accomplice, usually in exchange for a reduced sentence for themselves.
- undesirable discharge — a discharge under other than honorable conditions of a person from military service by administrative action.
- 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.
- university of iceland — (body, education) The Home of Fjolnir.
- 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.
- washington's birthday — February 22, formerly observed as a legal holiday in most states of the U.S. in honor of the birth of George Washington.
- watenstedt-salzgitter — former name of Salzgitter.
- whistling in the dark — If you say that someone is whistling in the dark, you mean that they are trying to remain brave and convince themselves that the situation is not as bad as it seems.
- white-crowned sparrow — a North American sparrow, Zonotrichia leucophrys, having black and white stripes on the head.
- wholesale price index — an indicator of price changes in the wholesale market
- with one's bare hands — If someone does something with their bare hands, they do it without using any weapons or tools.
- word association test — a technique for determining a subject's associative pattern by providing a verbal stimulus to which a verbal response is required.
- word-association test — a psychological test in which the person being tested responds to a given word with the first word (or the first word in a specified category, such as an antonym) brought to mind
- xeroderma pigmentosum — a rare inherited disease characterized by sensitivity to ultraviolet light, exposure resulting in lesions and tumors of the skin and eyes.
- yellow lady's-slipper — a showy orchid, Cypripedium calceolus, of eastern North America, having purple-tinged yellow flowers with an inflated lip petal.