21-letter words starting with s
- strategic air command — a U.S. Air Force command charged with intercontinental air strikes, especially nuclear attacks.
- strike the right note — to behave appropriately
- structural psychology — psychology centering on the analysis of the structure or content of conscious mental states by introspective methods.
- student participation — the extent to which students participate or involve themselves in a class, course, etc
- subjective complement — subject complement.
- subliminal perception — perception of or reaction to a stimulus that occurs without awareness or consciousness
- submerged arc welding — a type of heavy electric-arc welding using mechanically fed bare wire with the arc submerged in powdered flux to keep out oxygen
- subsistence allowance — money given in advance to a new soldier, employee, etc., to buy food, clothing, and pay for other necessities while awaiting a first pay.
- substitution instance — an expression so derived from another
- substitution reaction — the replacement of an atom or group of atoms in a compound by another atom or group.
- suction and curettage — a technique involving extraction of the fetus through a suction tube, used to perform abortions during the early stages of pregnancy.
- summary court-martial — a court-martial composed of one commissioned officer, authorized to try minor offenses against military law.
- sun protection factor — SPF.
- sunday school teacher — someone who teaches at a Sunday school
- supergranulation cell — one of a number of large convection cells in the photosphere and chromosphere of the sun, each having a diameter of 10,000–20,000 miles (16,000–32,000 km) and lasting longer than a day.
- supplementary benefit — (formerly) an extra amount of money that is paid to someone by the government, in addition to their normal income. Replaced by income support in 1988
- supply-side economics — a school of economic thought that emphasizes the importance to a strong economy of policies that remove impediments to supply
- surface acoustic wave — an acoustic wave generated on the surface of a piezoelectric substrate: used as a filter in electronic circuits
- surface friction drag — the part of the drag on a body moving through a fluid that is dependent on the nature of the surface of the body
- surface of projection — the surface upon which an image or a set of points is projected.
- surface of revolution — a surface formed by revolving a plane curve about a given line.
- surface-to-underwater — (of a missile, message, etc.) traveling from the surface of the earth to a target underwater.
- sweet spirit of nitre — ethyl nitrite spirit.
- swim against the tide — to resist prevailing opinion
- sympathetic vibration — a vibration induced by resonance.
- symphonie fantastique — a programmatic symphony (1830–31) in five movements by Hector Berlioz.
- synchronized shifting — gear shifting in which the gears to be meshed are made to rotate at the same speed.
- synchronized swimming — a sport growing out of water ballet in which swimmers, in solo, duet, and team efforts, complete various required figures by performing motions in relatively stationary positions, along with a freestyle competition, with the contestants synchronizing movements to music and being judged for body position, control, and the degree of difficulty of the moves.
- synchronous converter — a synchronous machine for converting alternating current to direct current, or vice versa, in which the armature winding is connected to collector rings and to a commutator.
- synchrotron radiation — electromagnetic radiation emitted by charged particles as they pass through magnetic fields.
- system management bus — (hardware, protocol) (SMBus, SMB) A simple two-wire bus used for communication with low-bandwidth devices on a motherboard, especially power related chips such as a laptop's rechargeable battery subsystem (see Smart Battery Data). Other devices might include temperature sensors and lid switches. A device can provide manufacturer information, indicate its model/part number, save its state for a suspend event, report different types of errors, accept control parameters, and return status. The SMB is generally not user configurable or accessible. The bus carries clock, data, and instructions and is based on Philip's I2C serial bus protocol. Support for SMBus devices is provided on Windows 2000. Windows 98 does not support such devices. The PIIX4 chipset provides SMBus functionality. Vendors using SMBus would be required to pay royalties.
- systeme international — Système International d'Unités