18-letter words containing a, n
- astrometric binary — a binary star that can be recognized as such because of its undulating proper motion.
- astronomical clock — a complex clock showing astronomical phenomena, such as the phases of the moon
- asynchronous logic — (architecture) A data-driven circuit design technique where, instead of the components sharing a common clock and exchanging data on clock edges, data is passed on as soon as it is available. This removes the need to distribute a common clock signal throughout the circuit with acceptable clock skew. It also helps to reduce power dissipation in CMOS circuits because gates only switch when they are doing useful work rather than on every clock edge. There are many kinds of asynchronous logic. Data signals may use either "dual rail encoding" or "data bundling". Each dual rail encoded Boolean is implemented as two wires. This allows the value and the timing information to be communicated for each data bit. Bundled data has one wire for each data bit and another for timing. Level sensitive circuits typically represent a logic one by a high voltage and a logic zero by a low voltage whereas transition signalling uses a change in the signal level to convey information. A speed independent design is tolerant to variations in gate speeds but not to propagation delays in wires; a delay insensitive circuit is tolerant to variations in wire delays as well. The purest form of circuit is delay-insensitive and uses dual-rail encoding with transition signalling. A transition on one wire indicates the arrival of a zero, a transition on the other the arrival of a one. The levels on the wires are of no significance. Such an approach enables the design of fully delay-insensitive circuits and automatic layout as the delays introduced by the layout compiler can't affect the functionality (only the performance). Level sensitive designs can use simpler, stateless logic gates but require a "return to zero" phase in each transition.
- at a rate of knots — very fast
- at one's wit's end — the last part or extremity, lengthwise, of anything that is longer than it is wide or broad: the end of a street; the end of a rope.
- at one's wits' end — at a loss to know how to proceed
- at sb's right hand — If someone is at a person's right hand, they work closely with that person so they can help and advise them.
- at someone's elbow — very close to someone; easy to reach
- at the instance of — at the suggestion or instigation of
- at the last minute — almost too late
- at your fingertips — If you say that something is at your fingertips, you approve of the fact that you can reach it easily or that it is easily available to you.
- at/from a distance — If you are at a distance from something, or if you see it or remember it from a distance, you are a long way away from it in space or time.
- atmospheric engine — an early form of single-acting engine in which the power stroke is provided by atmospheric pressure acting upon a piston in an exhausted cylinder.
- atmospheric window — wavelengths of the electromagnetic spectrum that can be transmitted through the earth's atmosphere. Atmospheric windows occur in the visible, infrared, and radio regions of the spectrum
- attendance figures — the number of people present at events such as football matches or concerts
- attendance officer — someone whose job is to keep records of students' attendance at school and to encourage students to attend
- attention-grabbing — An attention-grabbing remark or activity is one that is intended to make people notice it.
- attribution theory — the theory that tries to explain how people link actions and emotions to particular causes, both internal and external
- audio conferencing — the practice of conducting meetings by the use of audio telecommunications
- auditory phonetics — the branch of phonetics concerned with the perception of speech sounds by humans
- augmented interval — an interval that is a half step greater than the corresponding major or perfect interval
- australian doubles — an unusual formation in doubles in which the server's partner is positioned on the same side of the court as the server.
- australian terrier — a small wire-haired breed of terrier similar to the cairn
- australopithecines — Plural form of australopithecine.
- authorized version — the revised English translation of the Bible published in England in 1611 with the authorization of King James I
- autogenic training — a technique for reducing stress through mental exercises to produce physical relaxation
- autoignition point — the minimum temperature at which a substance will undergo spontaneous combustion.
- autoimmune disease — a disease resulting from a disordered immune reaction in which antibodies are produced against one's own tissues, as systemic lupus erythematosus or rheumatoid arthritis.
- autokinetic effect — apparent motion of a single point of light or a small object when presented on a dark field and observed continuously.
- automatic tracking — a radar tracking system in which an automatic device uses the echo signal from the tracked object to keep the radar constantly beamed on target and to compute the range of the object.
- autonomous phoneme — a phoneme that is defined or determined by its contrast in sound with other phonemes, without reference to its role in morphology or any other level of linguistic analysis beyond the phonetic level.
- auxiliary equation — characteristic equation (def 1b).
- auxiliary language — a language, as Esperanto, Swahili, or English, used for intercommunication by speakers of various other languages.
- auxiliary-equation — Mathematics. the characteristic polynomial of a given matrix, equated to zero. Also called auxiliary equation. an equation with one variable and equated to zero, which is derived from a given linear differential equation and in which the coefficient and power of the variable in each term correspond to the coefficient and order of a derivative in the original equation.
- available quantity — The available quantity of a product is the amount of that product available, or currently available in the store.
- aviation authority — a body that is responsible for overseeing the aviation industry
- aviation insurance — Aviation insurance is insurance cover for aircraft, and for damage, injury, or loss of life or cargo while traveling on aircraft.
- awnless bromegrass — Hungarian bromegrass.
- axile placentation — a type of placenta structure in an ovary with the ovules forming at the angles where the septa join the central placenta
- axis of revolution — an axis in a plane, about which an area is revolved to form a solid of revolution.
- ayatollah khomeini — Ayatollah Ruhollah [roo-hoh-luh;; Persian roo-haw-lah] /ruˈhoʊ lə;; Persian ˌru hɔˈlɑ/ (Show IPA), 1900?–89, Islamic leader of Iran 1979–89.
- bachelor apartment — a flat consisting of one room that is used as a sitting room and bedroom, as well as a kitchenette and a bathroom
- bachelor's-buttons — any of various plants of the daisy family with button-like flower heads
- back end generator — (tool) (BEG) A code generator developed by H. Emmelmann et al at GMD, University Karlsruhe, Germany. Its input language is Back End Generator Language (BEGL).
- back in the saddle — at work again
- back to square one — If you are back to square one, you have to start dealing with something from the beginning again because the way you were dealing with it has failed.
- back/down to earth — If you come down to earth or back to earth, you have to face the reality of everyday life after a period of great excitement.
- background reading — reading of related works in order to get contextual information on a topic that you are intending to study or write about
- backus normal form — Backus-Naur Form
- bad news/good news — If you say that something is bad news, you mean that it will cause you trouble or problems. If you say that something is good news, you mean that it will be useful or helpful to you.