| 释义 |
‖ sagitta|səˈdʒɪtə|
[L., lit. an arrow.]
1. Astr. A northern constellation lying between Hercules and Delphinus: = arrow n. 4.
1704in J. Harris Lex. Techn. I. [And in mod. Dicts.]
2. Geom.
a. The versed sine of an arc: = arrow n. 6.
[1594: see arrow n. 6.] 1704in J. Harris Lex. Techn. I. 1726 Leoni Alberti's Archit. I. 9/2 The..Line..from the middle Point of the Chord up to the Arch, leaving equal Angles on each Side, is call'd the Sagitta. 1853Sir H. Douglas Milit. Bridges (ed. 3) 32 The sagitta, or versed sine, of the curvature being about one fifth of the side of the triangle.
†b. In extended sense: The abscissa of a curve. Obs. rare—0.
1727–41in Chambers Cycl.
3. Arch. The key-stone of an arch.
1703R. Neve Builder's Dict. (1736). 1823P. Nicholson Pract. Build. 592. 1849–50 Weale Dict. Terms.
4. The middle horizontal stroke in the Greek letter ε. [App. an application of sense 2.]
1864Ellicott Pastoral Ep. (ed. 3) 103 The thickened extremity of the sagitta of ε. 1881Dublin Rev. VI. 134 The disputed line is really the sagitta of an epsilon.
5. Anat. ‘The sagittal suture’ (Cent. Dict. 1891).
6. Zool.
a. One of the otoliths of a fish's ear.
1888Rolleston & Jackson Anim. Life 86 There are [in the ear of the perch] generally two large otoliths, a sagitta in the sacculus, an asteriscus in the recessus cochleae. 1897Parker & Haswell Text-bk. Zool. II. 199.
b. One of the components of certain sponge-spicules: see quot.
1898Sedgwick Text-bk. Zool. I. 83 The Triæne consists of the rhabdome, or shaft, and the cladome, which consists of the three cladi, a straight line joining the ends of the two cladi is the chord. The sagitta is a perpendicular from the origin of the cladome to the chord. |