DIACOUSTIC
Di`a*cous"tic, a. Etym: [Pref. di- + acoustic.]
Defn: Pertaining to the science or doctrine of refracted sounds.
DIACOUSTICS
Di`a*cous"tics, n. Etym: [Cf. F. diacoustique.]
Defn: 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.
DIACRITIC; DIACRITICAL
Di`a*crit"ic, Di`a*crit"ic*al, a. Etym: [Gr. Critic.]
Defn: That separates or distinguishes; — applied to points or marks used to distinguish letters of similar form, or different sounds of the same letter, as, a, â, ä, o, ô, 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.
DIACTINIC
Di`ac*tin"ic, a. Etym: [Pref. di- + actinic.] (Physics)
Defn: Capable of transmitting the chemical or actinic rays of light; as, diactinic media.
DIADELPHIA
Di`a*del"phi*a, n.; pl. Etym: [NL., fr. Gr. (Bot.)
Defn: A Linnæan class of plants whose stamens are united into two bodies or bundles by their filaments.