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A-CHLAM-YD'E-OUS, a. [α neg. and Gr. χλαμυς, a garment.]

In botany, naked, having no floral envelop. – Lindley.


Achmitic augite spar. – Shepard.

A'CHOR, n. [Gr. αχωο, sordes capitis.]

  1. The scald head, a disease forming scaly eruptions, supposed to be a critical evacuation of acrimonious humors; a species of herpes. – Hooper. Quincy.
  2. In mythology, the god of flies, said to have been worshiped by the Cyreneans, to avoid being vexed by those insects. – Encyc.

A-CHRO-MAT'IC, a. [Gr. α privative and χρωμα, color.]

Destitute of color. Achromatic telescopes are formed of a combination of lenses, which separate the variously colored rays of light to equal angles of divergence, at different angles of refraction of the mean ray. In this case, the rays being made to refract towards contrary parts, the whole ray is caused to deviate from its course, without being separated into colors, and the optical aberration arising from the various colors of light, is prevented. This telescope is an invention of Dollond. – Nicholson.


State of being achromatic.

ACH-RO'MA-TISM, n. [Gr. α privative and χρωμα, color.]

  1. [1844] The destruction of the primary colors, which accompany the image of an object seen through a prism or lens. – Brande.
  2. [1841] The state of being achromatic. Brewster.

ACH'Y-RITE, n. [See Dioptase.]

A-CIC'U-LAE, n. [A-CIC'U-LÆ. plur. L. acicula.]

The prickles of some animals. – Knowles.

A-CIC'U-LAR, a. [L. acicula, Priscian, a needle, from Gr. ακη, L. acies, a point. See Acid.]

In the shape of a needle; having sharp points like needles. – Kirwan. Martyn. An acicular prism is when the crystals are slender and straight. – Phillips.

A-CIC'U-LAR-LY, adv.

In the manner of needles, or prickles.

AC'ID, a. [L. acidus; Sax. æced, vinegar; from the root of acies, edge; Gr. ακη; W. awc, an edge or point. See Edge.]

Sour, sharp or biting to the taste, having the taste of vinegar, as acid fruits or liquors.

AC'ID, n.

A compound capable of uniting with salifiable bases and thereby forming salts. An acid may be composed either of a simple or compound acidifiable base united with one or more acidifying principles. Those acids which were first recognized were sour to the taste (hence the name) and capable of reddening blue vegetable colors. Many acids are now known which have neither of these properties. An acid is always the electro-negative ingredient of a salt.

AC-I-DIF'ER-OUS, a. [Acid and L. fero.]

Containing acids, or an acid. Acidiferous minerals are such as consist of an earth combined with an acid; as carbonate of lime, aluminite, &c. – Phillips.

A-CID'I-FI-A-BLE, a. [From Acidify.]

Capable of being converted into an acid, by union with an acidifying principle.


The act or process of acidifying or changing into an acid.

A-CID'I-FI-ED, pp.

Made acid; converted into an acid.


A simple or compound principle, whose presence is necessary for acidity. The elementary acidifying principles are oxygen, chlorine, bromine, iodine, flourine, sulphur, selenium, and tellurium. Cyanogen may be named as an example of a compound acidifying principle, and probably there is one or two more. No acid is known which does not contain one of these substances.

A-CID'I-FY, v.t. [Acid and L. facio.]

To make acid; but appropriately to convert into an acid, chimically so called, by combination with any substance.

A-CID'I-FY-ING, ppr.

Making acid; converting into an acid; having power to change into an acid. Oxygen is called an acidifying principle or element.

AC-I-DIM'E-TER, n. [Acid and Gr. μετρον, measure.]

An instrument for ascertaining the strength of acids. – Ure.

A-CID'I-TY, n. [Fr. acidité, from acid.]

The quality of being sour; sourness; tartness; sharpness to the taste.


The quality of being sour; acidity.


Medicinal springs impregnated with sharp particles. – Knowles.

A-CID'U-LATE, v.t. [L. acidulus, slightly sour; Fr. aciduler, to make slightly sour. See Acid.]

To tinge with an acid; to make acid in a moderate degree. – Arbuthnot.


Tinged with an acid; made slightly sour.