2. (Astron.) The Dolphin, a constellation near the equator and east of Aquila.

Del"ta (?), n.; pl. Deltas (#). [Gr. de`lta, the name of the fourth letter of the Greek alphabet (the capital form of which is , Eng. D), from the Phœnician name of the corresponding letter. The Greeks called the alluvial deposit at the mouth of the Nile, from its shape, the Delta of the Nile.] A tract of land shaped like the letter delta (), especially when the land is alluvial and inclosed between two or more mouths of a river; as, the delta of the Ganges, of the Nile, or of the Mississippi.

Del`ta*fi*ca"tion (?), n. [Delta + L. facere to make.] The formation of a delta or of deltas. [R.]

Del*ta"ic (?), a. Relating to, or like, a delta.

||Del*thy"ris (?), n. [NL., fr. Gr. de`lta the name of the letter + thy`ra door.] (Zoöl.) A name formerly given to certain Silurian brachiopod shells of the genus Spirifer.

Delthyris limestone (Geol.), one of the divisions of the Upper Silurian rocks in New York.

Del"tic (?), a. Deltaic.

||Del*tid"i*um (?), n. [NL., fr. Gr. de`lta, the letter .] (Zoöl.) The triangular space under the beak of many brachiopod shells.

Del`to*he"dron (?), n. [Gr. de`lta, the letter + 'e`dra seat, base.] (Crystallog.) A solid bounded by twelve quadrilateral faces. It is a hemihedral form of the isometric system, allied to the tetrahedron.

Del"toid (?), a. [Gr. deltoeidh`s delta- shaped; de`lta the name of the letter + e'i^dos form: cf. F. deltoïde. See Delta.] Shaped like the Greek (delta); delta-shaped; triangular.

Deltoid leaf (Bot.), a leaf in the form of a triangle with the stem inserted at the middle of the base. -- Deltoid muscle (Anat.), a triangular muscle in the shoulder which serves to move the arm directly upward.

De*lud"a*ble (?), a. Capable of being deluded; liable to be imposed on; gullible. Sir T. Browne.

De*lude" (?), v. t. [imp. & p. p. Deluded; p. pr. & vb. n. Deluding.] [L. deludere, delusum; de- + ludere to play, make sport of, mock. See Ludicrous.] 1. To lead from truth or into error; to mislead the mind or judgment of; to beguile; to impose on; to dupe; to make a fool of.

To delude the nation by an airy phantom.

Burke.