(measure duration)
51Second — This article is about the unit of time. For other uses, see Second (disambiguation). A light flashing approximately once per second. The second (SI unit symbol: s; informal abbreviation: sec) is a unit of measurement of time, and is the… …
52Electrocardiogram — An electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm ) is a noninvasive transthoracic graphic produced by an electrocardiograph, which records the electrical activity of the heart over time. Its name is made of… …
53United Kingdom — a kingdom in NW Europe, consisting of Great Britain and Northern Ireland: formerly comprising Great Britain and Ireland 1801 1922. 58,610,182; 94,242 sq. mi. (244,100 sq. km). Cap.: London. Abbr.: U.K. Official name, United Kingdom of Great… …
54Breastfeeding — Suckling and nursing are synonyms. For other uses, see Nursing (disambiguation) and Suckling (disambiguation) An infant breastfeeding …
55space exploration — Investigation of the universe beyond Earth s atmosphere by means of manned and unmanned spacecraft. Study of the use of rockets for spaceflight began early in the 20th century. Germany s research on rocket propulsion in the 1930s led to… …
56Augustine — Gerard O’Daly 1 LIFE AND PHILOSOPHICAL READINGS Augustine was born in Thagaste (modern Souk Ahras in Algeria) in Roman North Africa in AD 354. He died as bishop of Hippo (now Annaba, Algeria) in 430. His education followed the standard Roman… …
57radar — /ray dahr/, n. 1. Electronics. a device for determining the presence and location of an object by measuring the time for the echo of a radio wave to return from it and the direction from which it returns. 2. a means or sense of awareness or… …
58History of radar — The history of radar starts with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. This possibility was suggested in James Clerk Maxwell s seminal work on electromagnetism.… …
59river — river1 riverless, adj. riverlike, adj. /riv euhr/, n. 1. a natural stream of water of fairly large size flowing in a definite course or channel or series of diverging and converging channels. 2. a similar stream of something other than water: a… …
60test — 1. To prove; to try a substance; to determine the chemical nature of a substance by means of reagents. 2. A method of examination, as to determine the presence or absence of a definite disease or of some substance in any of the fluids, tissues,… …
