<B>achromatic, </B>adjective.<DL COMPACT><DD><B> 1. </B>refracting white light without breaking it up into the colors of the spectrum. <BR> <I>Ex. an achromatic telescope.</I> <DD><B> 2. </B>without color; colorless. <DD><B> 3. </B>(Biology.) consisting of material stained with difficulty by the usual stains or dyes. <BR> <I>Ex. achromatic cells.</I> <DD><B> 4. </B>(Music.) without accidentals; not modulated. adv. <B>achromatically.</B> </DL>
<A NAME="achromaticity">
<B>achromaticity, </B>noun. =achromatism.</DL>
<A NAME="achromaticlens">
<B>achromatic lens,</B><DL COMPACT><DD> a compound lens corrected for chromatic aberration; achromat. </DL>
<A NAME="achromatin">
<B>achromatin, </B>noun.<DL COMPACT><DD> (Biology.) that portion of the mitotic cell nucleus or of individual chromosomes which, under the action of staining agents, remains less highly colored than the rest. </DL>
<A NAME="achromatism">
<B>achromatism, </B>noun.<DL COMPACT><DD><B> 1. </B>freedom from chromatic aberration. <DD><B> 2. </B>lack of color. </DL>
<A NAME="achromatize">
<B>achromatize, </B>transitive verb, <B>-tized,</B> <B>-tizing.</B><DL COMPACT><DD> to make achromatic; remove color from. noun <B>achromatization.</B> </DL>
<A NAME="achromatopsia">
<B>achromatopsia, </B>noun.<DL COMPACT><DD> total color blindness. </DL>
<A NAME="achromatous">
<B>achromatous, </B>adjective.<DL COMPACT><DD><B> 1. </B>lacking color. <DD><B> 2. </B>having less color than normal. </DL>
<B>Achtung, </B>interjection.<DL COMPACT><DD> (German.) attention! (used as a command or warning). </DL>
<A NAME="achy">
<B>achy, </B>adjective.<DL COMPACT><DD> (Informal.) full of aches. <BR> <I>Ex. [Crying] would only make her eyes achy and puffy and swollen in the morning (Shirley Ann Grau).</I> </DL>
<A NAME="acicle">
<B>acicle, </B>noun. =acicula.</DL>
<A NAME="acicula">
<B>acicula, </B>noun, pl. <B>-lae.</B><DL COMPACT><DD> a needlelike part. <BR> <I>Ex. The spines or bristles of some plants and the crystals of certain minerals are aciculae.</I> </DL>
<B>aciculum, </B>noun, pl. <B>-lums,</B> <B>-la.</B><DL COMPACT><DD> a slender needlelike part or bristly structure: <DD><B> a. </B>(Botany.) an acicula. <DD><B> b. </B>(Zoology.) a seta. </DL>
<A NAME="acid">
<B>acid, </B>noun, adjective.<DL COMPACT><DD><I>noun </I> <B>1a. </B>a chemical compound with a sour or bitter taste that usually unites with a base to form a salt. Acids have a <I>pH</I> value of less than 7. They change blue litmus paper to red and yield hydrogen ions in a water solution. Hydrochloric acid and sulfuric acid are two common kinds. <BR> <I>Ex. Certain bacteria cause some foods to form acids that eat their way slowly through the enamel of the teeth.</I> <DD><B> b. </B>any ionic or molecular substance which can give up a proton. <DD><B> c. </B>any molecule or ion that can attach itself to a pair of electrons from a base, forming a covalent bond. <DD><B> 2. </B>a substance with a sour taste like that of vinegar. <DD><B> 3. </B>(Slang.) LSD (lysergic acid diethylamide), a hallucinogen. <BR> <I>Ex. The hippies say there is not much acid (LSD) around now, but that grass (marijuana) is plentiful (New York Times).</I> <DD><I>adj. </I> <B>1. </B>of acids; having the properties of an acid. <BR> <I>Ex. Blue litmus paper turns red in an acid solution.</I> <DD><B> 2. </B>sharp or biting to the taste; sour. <BR> <I>Ex. Lemons are an acid fruit.</I> (SYN) tart. <DD><B> 3. </B>(Figurative.) sharp in manner or temper; caustic. <BR> <I>Ex. an acid tongue. Mother made an acid comment about my disorderly room.</I> <DD><B> 4. </B>containing a large proportion of silica; acidic. <BR> <I>Ex. Granite is an acid rock.</I> <DD><B> 5. </B>containing more acid than is normal. <DD><B> 6. </B>having a <I>pH</I> factor of less than 7; having a relatively high concentration of hydrogen ions (contrasted with <I>alkaline</I> especially as a characteristic of soil). adv. <B>acidly.</B> noun <B>acidness.</B> </DL>
<A NAME="aciddrop">
<B>acid drop,</B><DL COMPACT><DD> (British.) a candy made of sugar strongly flavored with tartaric acid. </DL>
<A NAME="acidfast">
<B>acid-fast, </B>adjective.<DL COMPACT><DD><B> 1. </B>retaining dye when treated with acid to remove the dye. <BR> <I>Ex. Tubercle bacilli are acid-fast.</I> <DD><B> 2. </B>differentiated by such a stain from closely related forms. noun <B>acid-fastness.</B> </DL>
<A NAME="acidfog">
<B>acid fog,</B><DL COMPACT><DD> fog containing a high concentration of acidity, resulting from pollutants emitted into the atmosphere. </DL>
<A NAME="acidforming">
<B>acid-forming, </B>adjective.<DL COMPACT><DD><B> 1. </B>producing a high proportion of acid residue during metabolism. <DD><B> 2. </B>acidiferous. </DL>
<A NAME="acidhead">
<B>acidhead, </B>noun.<DL COMPACT><DD> (Slang.) a person addicted to LSD. </DL>
<A NAME="acidic">
<B>acidic, </B>adjective.<DL COMPACT><DD><B> 1a. </B>forming acid. <DD><B> b. </B>of an acid or acids. <BR> <I>Ex. acidic ions.</I> <DD><B> c. </B>having the properties of an acid. <BR> <I>Ex. acidic resins.</I> <DD><B> 2. </B>(Figurative.) sharp and biting in manner or temper; caustic. <DD><B> 3. </B>containing a relatively large proportion of silica. <BR> <I>Ex. Granite is an acidic rock.</I> </DL>
<A NAME="acidiferous">
<B>acidiferous, </B>adjective.<DL COMPACT><DD> yielding an acid. </DL>
<A NAME="acidific">
<B>acidific, </B>adjective.<DL COMPACT><DD> producing acidity or an acid; acidifying. </DL>
<A NAME="acidification">
<B>acidification, </B>noun.<DL COMPACT><DD> the process of acidifying. </DL>
<A NAME="acidify">
<B>acidify, </B>transitive verb, intransitive verb, <B>-fied,</B> <B>-fying.</B><DL COMPACT><DD><B> 1a. </B>to make or become sour. <DD><B> b. </B>(Figurative.) to make caustic or turn sour. <BR> <I>Ex. His thin existence [was] all acidified into rage (Thomas Carlyle).</I> <DD><B> 2. </B>to change into an acid. <DD><B> 3. </B>to make or become acid. adj. <B>acidifiable.</B> noun <B>acidifier.</B> </DL>
<A NAME="acidimeter">
<B>acidimeter, </B>noun.<DL COMPACT><DD> an instrument for determining the strength of acids or acid solutions. </DL>
<A NAME="acidimetric">
<B>acidimetric, </B>adjective.<DL COMPACT><DD> of or involving acidimetry. </DL>
<B>acidimetry, </B>noun.<DL COMPACT><DD><B> 1. </B>measurement of the strength of acids. <DD><B> 2. </B>determination of the amount of free acid in a solution, as by titration. </DL>
<A NAME="acidity">
<B>acidity, </B>noun, pl. <B>-ties.</B><DL COMPACT><DD><B> 1a. </B>acid quality or condition; sourness. <BR> <I>Ex. the acidity of vinegar.</I> <DD><B> b. </B>(Figurative:) <BR> <I>Ex. The acidity of his remarks showed the disappointment in his defeat.</I> <DD><B> 2. </B>the degree of acid quality. <BR> <I>Ex. the acidity of a soil.</I> <DD><B> 3. </B>an excess of acid, especially hyperacidity. <DD><B> 4. </B>(Chemistry.) the number of replaceable--OH groups in the molecule of a base. </DL>
<B>acid jazz,</B><DL COMPACT><DD> music written in the style of jazz with rock rhythms and acid rock sound. <BR> <I>Ex. Far from the smoke-filled rooms, pulsating acid jazz music ... [she] tries to translate urban counterculture into marketable sneaker ideas (New York Times).</I> </DL>
<B>acid number,</B><DL COMPACT><DD> a number expressing the degree of acidity of a substance, equal to the number of milligrams of potassium hydroxide required to neutralize the free fatty acids in one gram of the substance; acid value. </DL>
<A NAME="acidophil">
<B>acidophil, </B>noun.<DL COMPACT><DD> a cell that stains readily with acid dyes. </DL>
<A NAME="acidophilic">
<B>acidophilic, </B>adjective.<DL COMPACT><DD> of or designating cells that stain with acid dyes. </DL>
<B>acidophilus milk,</B><DL COMPACT><DD> skim milk fermented by a bacterial culture, taken as part of a diet intended to change the bacterial content of the intestine. </DL>
<A NAME="acidosis">
<B>acidosis, </B>noun.<DL COMPACT><DD> a harmful condition in which the blood and tissues are less alkaline than is normal. </DL>
<A NAME="acidotic">
<B>acidotic, </B>adjective.<DL COMPACT><DD><B> 1. </B>of or having to do with acidosis. <DD><B> 2. </B>suffering from acidosis. </DL>
<A NAME="acidprocess">
<B>acid process,</B><DL COMPACT><DD> any steel-making process in which the furnace is lined with a siliceous substance and in which pig iron containing little phosphorus is used. </DL>
<A NAME="acidradical">
<B>acid radical,</B><DL COMPACT><DD> a radical formed from an organic acid by the removal from the acid of the univalent radical--OH (an atom of oxygen in combination with an atom of hydrogen); acyl. </DL>
<A NAME="acidrain">
<B>acid rain,</B><DL COMPACT><DD> rain that has a high concentration of sulfuric and nitric acids due to air pollution. <BR> <I>Ex. Scandinavian and American researchers suspect that acid rains have killed fish in many lakes in both regions (Boyce Rensberger).</I> </DL>
<A NAME="acidrock">
<B>acid rock,</B><DL COMPACT><DD> rock'n'roll music with sound and lyrics suggestive of hallucinatory or psychedelic experiences. </DL>
<A NAME="acidsalt">
<B>acid salt,</B><DL COMPACT><DD> a salt formed from an acid of which only part of the hydrogen has been replaced by a metal or radical. </DL>
