An instrument used to monitor the operation or condition of an engine, furnace, electrical network, reservoir, or other physical system; a meter or gauge.
The needle, dial, or other registering device on such an instrument.
Chemistry Any of various substances, such as litmus or phenolphthalein, that indicate the presence, absence, or concentration of another substance or the degree of reaction between two or more substances by means of a characteristic change, especially in color.
Ecology A plant or animal whose existence in an area is strongly indicative of specific environmental conditions.
Any of various statistical values that together provide an indication of the condition or direction of the economy.
a number or ratio (a value on a scale of measurement) derived from a series of observed facts; can reveal relative changes as a function of time [syn: index]
2.
a signal for attracting attention
3.
a device for showing the operating condition of some system
4.
(chemistry) a substance that changes color to indicate the presence of some ion or substance; can be used to indicate the completion of a chemical reaction or (in medicine) to test for a particular reaction
indicatorAudio Help (ĭn'dĭ-kā'tər) Pronunciation Key
A chemical compound that changes color and structure when exposed to certain conditions and is therefore useful for chemical tests. Litmus, for example, is an indicator that becomes red in the presence of acids and blue in the presence of bases.
Card\, n. [F. carte, fr. L. charta paper, Gr. ? a leaf of paper. Cf. Chart.]1. A piece of pasteboard, or thick paper, blank or prepared for various uses; as, a playing card; a visiting card; a card of invitation; pl. a game played with cards. Our first cards were to Carabas House. --Thackeray. 2. A published note, containing a brief statement, explanation, request, expression of thanks, or the like; as, to put a card in the newspapers. Also, a printed programme, and (fig.), an attraction or inducement; as, this will be a good card for the last day of the fair. 3. A paper on which the points of the compass are marked; the dial or face of the mariner's compass. All the quartere that they know I' the shipman's card. --Shak. 4. (Weaving) A perforated pasteboard or sheet-metal plate for warp threads, making part of the Jacquard apparatus of a loom. See Jacquard. 5. An indicator card. See under Indicator. Business card, a card on which is printed an advertisement or business address. Card basket (a) A basket to hold visiting cards left by callers. (b) A basket made of cardboard. Card catalogue. See Catalogue. Card rack, a rack or frame for holding and displaying business or visiting card. Card table, a table for use inplaying cards, esp. one having a leaf which folds over. On the cards, likely to happen; foretold and expected but not yet brought to pass; -- a phrase of fortune tellers that has come into common use; also, according to the programme. Playing card, cards used in playing games; specifically, the cards cards used playing which and other games of chance, and having each pack divided onto four kinds or suits called hearts, diamonds, clubs, and spades. The full or whist pack contains fifty-two cards. To have the cards in one's own hands, to have the winning cards; to have the means of success in an undertaking. To play one's cards well, to make no errors; to act shrewdly. To play snow one's cards, to expose one's plants to rivals or foes. To speak by the card, to speak from information and definitely, not by guess as in telling a ship's bearing by the compass card. Visiting card, a small card bearing the name, and sometimes the address, of the person presenting it.
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