| 释义 |
semicircle|ˈsɛmɪsɜːk(ə)l|
[ad. L. sēmicirculus: see semi- 7 b and circle n.]
1. The half of a circle divided by a diameter, or the half of its circumference.
1526A C. mery talys 3 b, [Oxford scholar loq.] Cobler I pray the set me .ii. tryangyls & .ii. semy cercles vppon my subpedytals. 1551Recorde Pathw. Knowl. i. Defin., If that part be separate from the rest of the circle..And if it be parted juste by the centre..then is it called a semicircle, or halfe compasse. 1571Digges Pantom. i. B ij, A Semi⁓circle or halfe Circle, doth conteine both the Dimetient and Centre of his circle, with the precise halfe of his circumference. 1610Holland Camden's Brit. i. 208 A very antient towne..situat amidst hilles in forme of a semicircle. 1667Primatt City & C. Builder 164 The measuring of a Semi⁓circle, is the multiplying half the Diameter..by a quarter of the Circle. 1798Hutton Course Math. I. 301 An Angle in a Semicircle, is a Right Angle.
2. A set of objects or an arrangement in the form of a half-circle; a semicircular form, formation, structure, etc.
1597A. M. tr. Guillemeau's Fr. Chirurg. 27/1 We must file of all such teeth which will not be contayned in the semicircle of the other teeth. 1636B. Jonson Eng. Gram. ii. i. (1640) 70 Apostrophus..should, and of the learneder sort hath his signe and marke, which is such a Semicircle ' placed in the top. a1674Clarendon Hist. Reb. xv. §54 The smaller ships..lay in a semicircle moored along the shore. 1726Swift Gulliver i. i, The Chains..gave me..the Liberty of walking backwards and forwards in a Semicircle. 1817Shelley Rev. Islam i. 168 The pallid semicircle of the moon. 1831in Jrnl. Frankl. Inst. VIII. (N.S.) 195 The teeth being placed on a fixed semi-circle. 1837Penny Cycl. IX. 129/1 The semicircle of the orchestra. 1874Black Pr. Thule ii, The harbour was overlooked by a semicircle of hills.
fig.a1619Beaum. & Fl. Q. Corinth iv. i, Has he given the lye In circle, or oblique, or semi-circle, Or direct parrallel? you must challenge him.
3. A semicircular instrument or one marked with a semicircle; now only = graphometer.
1594Blundevil Exerc. iv. (1597) 209 Another Circle of brasse plate..called the semi-Circle of position, which serueth chiefly for matters of Astronomie, as to find out the twelu houses of heauen. 1701Moxon Math. Instr. 18 Semicircle, made of Brass, with an Index and sights, Box and Needle, Ball and Socket, and Staff; containing 180 Degrees, being half the Theodolet. 1712J. James tr. Le Blond's Gardening 81 Instruments made use of for tracing upon the Ground..are the Graphometre, or Semi-circle. a1859Macaulay Hist. Eng. xxiv. V. 133 They meet at the corner of his park with paper and pencils, a pole, a chain and a semicircle, measure his fields.
Hence ˈsemicircle v. trans., to surround with a semicircle; intr. to form a semicircle.
1813Shelley Q. Mab i. 235 An immense concave..semi⁓circled with a belt Flashing incessant meteors. a1864Hawthorne Amer. Note-bks. (1879) II. 124 A broad streak..semicircling beneath either eye. |