Part 248

Di`a*caus"tic, n. 1. (Med.) That which burns by refraction, as a double convex lens, or the sun's rays concentrated by such a lens, sometimes used as a cautery.

2. (Math.) A curved formed by the consecutive intersections of rays of light refracted through a lens.

{ ||Di*ach"y*lon (?), ||Di*ach"y*lum (?), } n. [NL. diachylum, fr. Gr. &?; very juicy; dia` thoroughly + &?; juice.] (Med. & Chem.) A plaster originally composed of the juices of several plants (whence its name), but now made of an oxide of lead and oil, and consisting essentially of glycerin mixed with lead salts of the fat acids.

Di*ac"id (?), a. [Pref. di- + acid.] (Chem.) Divalent; -- said of a base or radical as capable of saturating two acid monad radicals or a dibasic acid. Cf. Dibasic, a., and Biacid.

||Di`a*co"di*um (?), n. [L., from Gr. &?; &?; from poppy heads; dia` through, from + &?; head, a poppy head.] A sirup made of poppies.

Di*ac"o*nal (?), a. [LL. diaconalis: cf. F. diaconal. Cf. Deacon.] Of or pertaining to a deacon.

Di*ac"o*nate (?), n. [L. diaconatus: cf. F. diaconat.] The office of a deacon; deaconship; also, a body or board of deacons.

Di*ac"o*nate, a. Governed by deacons. "Diaconate church." T. Goodwin.

||Di*ac"o*pe (?), n. [L., fr. Gr. &?; a cutting in two; dia` through + &?;.] (Gram.) Tmesis.

Di`a*cous"tic (?), a. [Pref. di- + acoustic.] Pertaining to the science or doctrine of refracted sounds.

Di`a*cous"tics (?), n. [Cf. F. diacoustique.] That branch of natural philosophy which treats of the properties of sound as affected by passing through different mediums; -- called also diaphonics. See the Note under Acoustics.

{ Di`a*crit"ic (?), Di`a*crit"ic*al (?), } a. [Gr. &?;, fr. &?; to separate, distinguish; dia` through + &?; to separate. See Critic.] That separates or distinguishes; -- applied to points or marks used to distinguish letters of similar form, or different sounds of the same letter, as, , , ä, , , etc. "Diacritical points." Sir W. Jones.

A glance at this typography will reveal great difficulties, which diacritical marks necessarily throw in the way of both printer and writer.

A. J. Ellis.

Di`ac*tin"ic (?), a. [Pref. di- + actinic.] (Physics) Capable of transmitting the chemical or actinic rays of light; as, diactinic media.

||Di`a*del"phi*a (?), n. pl. [NL., fr. Gr. di- = di`s- twice + &?; brother.] (Bot.) A Linnæan class of plants whose stamens are united into two bodies or bundles by their filaments.

{ Di`a*del"phi*an (?), Di`a*del"phous (?), } a. [Cf. F. diadelphe.] (Bot.) Of or pertaining to the class Diadelphia; having the stamens united into two bodies by their filaments (said of a plant or flower); grouped into two bundles or sets by coalescence of the filaments (said of stamens).

Di"a*dem (?), n. [F. diadème, L. diadema, fr. Gr. &?;, fr. &?; to bind round; dia` through, across + &?; to bind; cf. Skr. d to bind.] 1. Originally, an ornamental head band or fillet, worn by Eastern monarchs as a badge of royalty; hence (later), also, a crown, in general. "The regal diadem." Milton.

2. Regal power; sovereignty; empire; -- considered as symbolized by the crown.

3. (Her.) An arch rising from the rim of a crown (rarely also of a coronet), and uniting with others over its center.

Diadem lemur. (Zoöl.) See Indri. -- Diadem spider (Zoöl.), the garden spider.

Di"a*dem, v. t. To adorn with a diadem; to crown.

Not so, when diadem'd with rays divine.

Pope.

To terminate the evil, To diadem the right.

R. H. Neale.

Di"a*drom (?), n. [Gr. &?; a running through; dia` through + &?;, used as inf. aor. of &?; to run.] A complete course or vibration; time of vibration, as of a pendulum. [Obs.] Locke.

{ Di*ær"e*sis, Di*er"e*sis } (?; 277), n.; pl. Diæreses or Diereses (#). [L. diaeresis, Gr. &?;, fr. &?; to divide; dia` through, asunder + &?; to take. See Heresy.] 1. (Gram.) The separation or resolution of one syllable into two; -- the opposite of synæresis.