a
Libration Li*bra"tion (l[-i]*br[=a]"sh[u^]n), n. [L. libratio: cf. F. libration.] 1. The act or state of librating. --Jer. Taylor. [1913 Webster]

2. (Astron.) A real or apparent libratory motion, like that of a balance before coming to rest. [1913 Webster]

{Libration of the moon}, any one of those small periodical changes in the position of the moon's surface relatively to the earth, in consequence of which narrow portions at opposite limbs become visible or invisible alternately. It receives different names according to the manner in which it takes place; as: {(a)} Libration in longitude, that which, depending on the place of the moon in its elliptic orbit, causes small portions near the eastern and western borders alternately to appear and disappear each month. ({b}) Libration in latitude, that which depends on the varying position of the moon's axis in respect to the spectator, causing the alternate appearance and disappearance of either pole. ({c}) Diurnal or parallactic libration, that which brings into view on the upper limb, at rising and setting, some parts not in the average visible hemisphere. [1913 Webster]


The Collaborative International Dictionary of English. 2000.

Look at other dictionaries:

  • A — ([.a] emph. [=a]). 1. [Shortened form of an. AS. [=a]n one. See {One}.] An adjective, commonly called the indefinite article, and signifying one or any, but less emphatically. At a birth ; In a word ; At a blow . Shak. Note: It is placed before… …   The Collaborative International Dictionary of English

  • Ä — or ä , is a character which represents either a letter from several extended Latin alphabets, or the letter A with umlaut or diaeresis. As an independent letter The letter Ä occurs in the Swedish, Finnish, Estonian, and Slovak alphabets, where i …   Wikipedia

  • A — (named [=a] in the English, and most commonly [ a] in other languages). The first letter of the English and of many other alphabets. The capital A of the alphabets of Middle and Western Europe, as also the small letter (a), besides the forms in… …   The Collaborative International Dictionary of English

  • A — ([.a]), prep. [Abbreviated form of an (AS. on). See {On}.] 1. In; on; at; by. [Obs.] A God s name. Torn a pieces. Stand a tiptoe. A Sundays Shak. Wit that men have now a days. Chaucer. Set them a work. Robynson (More s Utopia). [1913 Webster] 2.… …   The Collaborative International Dictionary of English

  • A- — A, as a prefix to English words, is derived from various sources. (1) It frequently signifies on or in (from an, a forms of AS. on), denoting a state, as in afoot, on foot, abed, amiss, asleep, aground, aloft, away (AS. onweg), and analogically,… …   The Collaborative International Dictionary of English

  • A — [From AS. of off, from. See {Of}.] Of. [Obs.] The name of John a Gaunt. What time a day is it ? Shak. It s six a clock. B. Jonson. [1913 Webster] …   The Collaborative International Dictionary of English

  • A — A barbarous corruption of have, of he, and sometimes of it and of they. So would I a done A brushes his hat. Shak. [1913 Webster] …   The Collaborative International Dictionary of English

  • A — An expletive, void of sense, to fill up the meter [1913 Webster] A merry heart goes all the day, Your sad tires in a mile a. Shak. [1913 Webster] …   The Collaborative International Dictionary of English

  • a — I. noun (plural a s or as) Usage: often capitalized, often attributive Date: before 12th century 1. a. the 1st letter of the English alphabet b. a graphic representation of this letter c. a speech counterpart of orthographic a 2. the sixth tone… …   New Collegiate Dictionary

  • A — s. m. La première lettre de notre alphabet, et la première des voyelles. La lettre A. Un grand A. Un petit a. Un A majuscule. Un a romain. Un a italique. Des a mal formés. La voyelle A. A est long dans Blâme. A est bref dans Glace. A, dans les… …   Dictionnaire de l'Academie Francaise, 7eme edition (1835)

  • À — préposition Lorsque à précède l’article masculin suivi d’une consonne ou d’un h aspiré, il se contracte en au. Il fait au pluriel aux. Il exprime cinq rapports différents : 1° Possession; 2° Tendance, direction vers un lieu, vers un objet; 3°… …   Dictionnaire de l'Academie Francaise, 8eme edition (1935)

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”