Achenial A·che"ni·al adjective Pertaining to an achene.

Acheron Ach"e·ron noun [ Latin , from Greek ....] (Myth.) A river in the Nether World or infernal regions; also, the infernal regions themselves. By some of the English poets it was supposed to be a flaming lake or gulf. Shak.

Acherontic Ach`e·ron"tic adjective Of or pertaining to Acheron; infernal; hence, dismal, gloomy; moribund.

Achievable A·chiev"a·ble adjective Capable of being achieved. Barrow.

Achievance A·chiev"ance noun [ Confer Old French achevance .] Achievement. [ Obsolete] Sir T. Elyot.

Achieve A·chieve" transitive verb [ imperfect & past participle Achieved ; present participle & verbal noun Achieving ] [ Middle English acheven , Old French achever , achiever , French achever , to finish; à (L. ad ) + Old French chief , French chef , end, head, from Latin caput head. See Chief .] 1. To carry on to a final close; to bring out into a perfected state; to accomplish; to perform; -- as, to achieve a feat, an exploit, an enterprise.

Supposing faculties and powers to be the same, far more may be achieved in any line by the aid of a capital, invigorating motive than without it.
I. Taylor.

2. To obtain, or gain, as the result of exertion; to succeed in gaining; to win.

Some are born great, some achieve greatness.
Shak.

Thou hast achieved our liberty.
Milton.

[ [Obs]., with a material thing as the aim.]

Show all the spoils by valiant kings achieved .
Prior.

He hath achieved a maid
That paragons description.
Shak.

3. To finish; to kill. [ Obsolete] Shak.

Syn. -- To accomplish; effect; fulfill; complete; execute; perform; realize; obtain. See Accomplish .

Achievement A·chieve"ment (-m e nt) noun [ Confer French achèvement , English Hatchment .] 1. The act of achieving or performing; an obtaining by exertion; successful performance; accomplishment; as, the achievement of his object.

2. A great or heroic deed; something accomplished by valor, boldness, or praiseworthy exertion; a feat.

[ The exploits] of the ancient saints . . . do far surpass the most famous achievements of pagan heroes.
Barrow.

The highest achievements of the human intellect.
Macaulay.

3. (Her.) An escutcheon or ensign armorial; now generally applied to the funeral shield commonly called hatchment . Cussans.

Achiever A·chiev"er noun One who achieves; a winner.

Achillean Ach`il·le"an adjective Resembling Achilles, the hero of the Iliad; invincible.

Achilles' tendon A·chil"les' ten"don noun [ Latin Achillis tendo .] (Anat.) The strong tendon formed of the united tendons of the large muscles in the calf of the leg, an inserted into the bone of the heel; -- so called from the mythological account of Achilles being held by the heel when dipped in the River Styx.

Achilous A·chi"lous adjective [ Greek 'a priv. + ... lip.] (Botany) Without a lip.

Aching Ach"ing adjective That aches; continuously painful. See Ache . -- Ach"ing*ly , adverb

The aching heart, the aching head.
Longfellow.

Achiote A`chi·o"te noun [ Spanish achiote , from Indian achiotl .] Seeds of the annotto tree; also, the coloring matter, annotto.

Achlamydate A·chlam"y·date adjective [ Greek 'a priv. + .... .... a short cloak.] (Zoology) Not possessing a mantle; -- said of certain gastropods.

Achlamydeous Ach`la·myd"e·ous adjective (Botany) Naked; having no floral envelope, neither calyx nor corolla.

Acholia A·cho"li·a noun [ New Latin , from Greek ...; 'a priv. + ... bile.] (Medicine) Deficiency or want of bile.

Acholous Ach"o·lous adjective (Medicine) Lacking bile.

Achromatic Ach`ro·mat"ic adjective [ Greek ... colorless; 'a priv. + ..., ..., color: confer French achromatique .] 1. (Opt.) Free from color; transmitting light without decomposing it into its primary colors.

2. (Biol.) Uncolored; not absorbing color from a fluid; -- said of tissue.

Achromatic lens (Opt.) , a lens composed usually of two separate lenses, a convex and concave, of substances having different refractive and dispersive powers, as crown and flint glass, with the curvatures so adjusted that the chromatic aberration produced by the one is corrected by other, and light emerges from the compound lens undecomposed. -- Achromatic prism . See Prism . -- Achromatic telescope , or microscope , one in which the chromatic aberration is corrected, usually by means of a compound or achromatic object glass, and which gives images free from extraneous color.

Achromatically Ach`ro·mat"ic·al·ly adverb In an achromatic manner.

Achromaticity Ach`ro·ma·tic"i·ty noun Achromatism.

Achromatin A·chro"ma·tin noun (Biol.) Tissue which is not stained by fluid dyes. W. Flemming.

Achromatism A·chro"ma·tism noun [ Confer French achromatisme .] The state or quality of being achromatic; as, the achromatism of a lens; achromaticity. Nichol.

Achromatization A·chro`ma·ti·za"tion noun [ Confer French achromatisation .] The act or process of achromatizing.

Achromatize A·chro"ma·tize transitive verb [ imperfect & past participle Achromatized ; present participle & verbal noun Achromatizing ] [ Greek 'a priv. + ... color.] To deprive of color; to make achromatic.

Achromatopsy A·chro"ma·top"sy noun [ Greek 'a priv. + ... color + ... sight.] Color blindness; inability to distinguish colors; Daltonism.

Achromatous A·chro"ma·tous adjective [ See Ahromatic .] Lacking, or deficient in, color; as, achromatous blood.

Achromic A·chro"mic adjective [ Greek ... colorless; ... priv. + ... color.] Free from color; colorless; as, in Physiol. Chem. , the achromic point of a starch solution acted upon by an amylolytic enzyme is the point at which it fails to give any color with iodine.

Achronic A·chron"ic adjective See Acronyc .

Achroous Ach"ro·ous adjective [ Greek ...; 'a priv. + ... color.] Colorless; achromatic.

Achroödextrin Ach`ro·ö·dex"trin noun [ Greek ... colorless + English dextrin .] (Physiol. Chem.) Dextrin not colorable by iodine. See Dextrin .

Achylous A·chy"lous adjective [ Greek ... without juice.] (Physiol.) Without chyle.

Achymous A·chy"mous adjective [ Greek ... without juice.] (Physiol.) Without chyme.

Achæan, Achaian A·chæ"an, A·cha"ian adjective [ Latin Achaeus , Achaius ; Greek ....] Of or pertaining to Achaia in Greece; also, Grecian. -- noun A native of Achaia; a Greek.

Acicula A·cic"u·la noun ; plural Aciculæ [ Latin , a small needle, dimin. of acus needle.] (Nat. Hist.) One of the needlelike or bristlelike spines or prickles of some animals and plants; also, a needlelike crystal.

Acicular A·cic"u·lar adjective Needle-shaped; slender like a needle or bristle, as some leaves or crystals; also, having sharp points like needles.

Aciculate, Aciculated A·cic"u·late, A·cic"u·la"ted adjective (Nat. Hist.) (a) Furnished with aciculæ. (b) Acicular. (c) Marked with fine irregular streaks as if scratched by a needle. Lindley.

Aciculiform A·cic"u·li·form adjective [ Latin acicula needle + -form .] Needle-shaped; acicular.

Aciculite A·cic"u·lite noun (Min.) Needle ore. Brande & C.

Acid Ac"id adjective [ Latin acidus sour, from the root ak to be sharp: confer French acide . Confer Acute .] 1. Sour, sharp, or biting to the taste; tart; having the taste of vinegar: as, acid fruits or liquors. Also fig.: Sour- tempered.

He was stern and his face as acid as ever.
A. Trollope.

2. Of or pertaining to an acid; as, acid reaction.

Acid Ac"id noun 1. A sour substance.

2. (Chemistry) One of a class of compounds, generally but not always distinguished by their sour taste, solubility in water, and reddening of vegetable blue or violet colors. They are also characterized by the power of destroying the distinctive properties of alkalies or bases, combining with them to form salts, at the same time losing their own peculiar properties. They all contain hydrogen, united with a more negative element or radical, either alone, or more generally with oxygen, and take their names from this negative element or radical. Those which contain no oxygen are sometimes called hydracids in distinction from the others which are called oxygen acids or oxacids .

» In certain cases, sulphur, selenium, or tellurium may take the place of oxygen, and the corresponding compounds are called respectively sulphur acids or sulphacids , selenium acids , or tellurium acids . When the hydrogen of an acid is replaced by a positive element or radical, a salt is formed, and hence acids are sometimes named as salts of hydrogen; as hydrogen nitrate for nitric acid, hydrogen sulphate for sulphuric acid, etc. In the old chemistry the name acid was applied to the oxides of the negative or nonmetallic elements, now sometimes called anhydrides .

Acid process Ac"id proc"ess (Iron Metal.) That variety of either the Bessemer or the open-hearth process in which the converter or hearth is lined with acid, that is, highly siliceous, material. Opposed to basic process .

Acidic A·cid"ic adjective (Min.) Containing a high percentage of silica; -- opposed to basic .

Acidiferous Ac`id·if"er·ous adjective [ Latin acidus sour + -ferous .] Containing or yielding an acid.

Acidifiable A·cid"i·fi`a·ble adjective Capable of being acidified, or converted into an acid.

Acidific Ac`id·if"ic adjective Producing acidity; converting into an acid. Dana.

Acidification A·cid`i·fi·ca"tion noun [ Confer French acidification .] The act or process of acidifying, or changing into an acid.

Acidifier A·cid"i·fi`er noun (Chemistry) A simple or compound principle, whose presence is necessary to produce acidity, as oxygen, chlorine, bromine, iodine, etc.

Acidify A·cid"i·fy transitive verb [ imperfect & past participle Acidified ; present participle & verbal noun Acidifying ] [ Latin acidus sour, acid + -fy : confer French acidifier .] 1. To make acid; to convert into an acid; as, to acidify sugar.

2. To sour; to imbitter.

His thin existence all acidified into rage.
Carlyle.

Acidimeter Ac`id·im"e·ter noun [ Latin acidus acid + -meter .] (Chemistry) An instrument for ascertaining the strength of acids. Ure.

Acidimetry Ac`id·im"e·try noun [ Latin acidus acid + -metry .] (Chemistry) The measurement of the strength of acids, especially by a chemical process based on the law of chemical combinations, or the fact that, to produce a complete reaction, a certain definite weight of reagent is required. -- Ac`id*i*met"ric*al adjective

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