Equivalent E*quiv"a*lent ([-e]*kw[i^]v"[.a]*lent), n. 1. Something equivalent; that which is equal in value, worth, weight, or force; as, to offer an equivalent for damage done. [1913 Webster]

He owned that, if the Test Act were repealed, the Protestants were entitled to some equivalent. . . . During some weeks the word equivalent, then lately imported from France, was in the mouths of all the coffeehouse orators. --Macaulay. [1913 Webster]

2. (Chem.) That comparative quantity by weight of an element which possesses the same chemical value as other elements, as determined by actual experiment and reference to the same standard. Specifically: (a) The comparative proportions by which one element replaces another in any particular compound; thus, as zinc replaces hydrogen in hydrochloric acid, their equivalents are 32.5 and 1. (b) The combining proportion by weight of a substance, or the number expressing this proportion, in any particular compound; as, the equivalents of hydrogen and oxygen in water are respectively 1 and 8, and in hydric dioxide 1 and 16. [1913 Webster]

Note: This term was adopted by Wollaston to avoid using the conjectural expression atomic weight, with which, however, for a time it was practically synonymous. The attempt to limit the term to the meaning of a universally comparative combining weight failed, because of the possibility of several compounds of the substances by reason of the variation in combining power which most elements exhibit. The equivalent was really identical with, or a multiple of submultiple of, the atomic weight. [1913 Webster]

3. (Chem.) A combining unit, whether an atom, a radical, or a molecule; as, in acid salt two or more equivalents of acid unite with one or more equivalents of base. [1913 Webster]

{Mechanical equivalent of heat} (Physics), originally defined as the number of units of work which the unit of heat can perform, equivalent to the mechanical energy which must be expended to raise the temperature of a pound of water one degree Fahrenheit; later this value was defined as one {British thermal unit} (B.t.u). Its value was found by Joule to be 772 foot pounds; later measurements give the value as 777.65 foot-pounds, equivalent to 107.5 kg-meters. This value was originally called Joule's equivalent, but the modern Joule is defined differently, being 10^{7} ergs. The B.t.u. is now given as 1,054.35 absolute Joules, and therefore 1 calorie (the amount of heat needed to raise one gram of water one degree centigrade) is equivalent to 4.186 Joules. [1913 Webster + PJC]

Note: The original definition of the Mechanical equivalent of heat in the 1913 Webster was as below. The difference between foot pounds and kilogram-meters ("on the centigrade scale") is puzzling as it should be a factor of 7.23, and the figure given for kilogram-meters may be a mistaken misinterpretation of the report. -- PJC: The number of units of work which the unit of heat can perform; the mechanical energy which must be expended to raise the temperature of a unit weight of water from 0[deg] C. to 1[deg] C., or from 32[deg] F. to 33[deg] F. The term was introduced by Dr. Mayer of Heilbronn. Its value was found by Joule to be 1390 foot pounds upon the Centigrade, or 772 foot pounds upon the Fahrenheit, thermometric scale, whence it is often called {Joule's equivalent}, and represented by the symbol J. This is equal to 424 kilogram meters (Centigrade scale). A more recent determination by Professor Rowland gives the value 426.9 kilogram meters, for the latitude of Baltimore. [1913 Webster +PJC]

The Collaborative International Dictionary of English. 2000.


Look at other dictionaries:

  • équivalent — équivalent, ente (é ki va lan, lan t ) adj. 1°   Qui équivaut, qui est de même valeur. Rendre un service équivalent à celui que l on a reçu. 2°   Terme de géométrie. Il se dit des surfaces ou des volumes qui ont les mêmes contenances sans avoir… …   Dictionnaire de la Langue Française d'Émile Littré

  • equivalent — e‧quiv‧a‧lent [ɪˈkwɪvlənt] noun [countable] something that is equal in value, amount, quality etc to something else: • The Japanese bank had the equivalent of $131 billion in assets on March 31. equivalent adjective : • It must issue 5 million… …   Financial and business terms

  • equivalent — eq·uiv·a·lent n: something that performs substantially the same function as another thing in substantially the same way compare aggregation, combination, invention ◇ Under patent law, a patentee may bring a claim for infringement against the… …   Law dictionary

  • Equivalent — Équivalent Pour les articles homonymes, voir équivalence. La notion d équivalence permet de dire précisément et « mathématiquement » quand deux fonctions ou deux suites ont le même comportement au voisinage d un point ou de l infini.… …   Wikipédia en Français

  • Equivalent — E*quiv a*lent ([ e]*kw[i^]v [.a]*lent), a. [L. aequivalens, entis, p. pr. of aequivalere to have equal power; aequus equal + valere to be strong, be worth: cf. F. [ e]quivalent. See {Equal}, and {Valiant}.] 1. Equal in worth or value, force,… …   The Collaborative International Dictionary of English

  • equivalent — (adj.) early 15c., from M.Fr. equivalent and directly from L.L. aequivalentem (nom. aequivalens) equivalent, prp. of aequivalere be equivalent, from L. aequus equal (see EQUAL (Cf. equal)) + valere be well, be worth (see VALIANT (Cf …   Etymology dictionary

  • equivalent — Equivalent, [equival]ente. adv. Qui est de mesme prix, de mesme valeur. Je luy donneray un heritage equivalent. une chose equivalente. Il est aussi subst. On n a pu le remettre en possession des villes qu on luy avoit prises, mais on luy en a… …   Dictionnaire de l'Académie française

  • equivalent — ► ADJECTIVE (often equivalent to) 1) equal in value, amount, function, meaning, etc. 2) having the same or a similar effect. ► NOUN ▪ a person or thing that is equivalent to another. DERIVATIVES equivalence noun equivalency noun …   English terms dictionary

  • Equivalent — E*quiv a*lent, v. t. To make the equivalent to; to equal; equivalence. [R.] [1913 Webster] …   The Collaborative International Dictionary of English

  • equivalent — [adj] same, similar agnate, akin, alike, analogous, carbon*, commensurate, comparable, convertible, copy, correlative, correspondent, corresponding, ditto*, duplicate, equal, even, homologous, identical, indistinguishable, interchangeable, like,… …   New thesaurus

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