centroidn.

Brit.

/ˈsɛntrɔɪd/, U.S.

/ˈsɛnˌtrɔɪd/

Forms: 1800s– centroïd, 1800s– centroid, 1900s– centeroid.

Origin: Formed within English, by derivation. Etymons: centre n.¹, -oid suffix.

Etymology: < centre n.¹ + -oid suffix.In later use in sense 3 (in quot. 1876 and later) after cardioid n., cycloid n., and other names of curves; subsequently superseded by centrode n.

†1. With reference to a circle represented by an ellipse in the perspective of a given drawing: the point in the interior of the circle that corresponds to the centre of the ellipse. Obsolete. rare.

ΚΠ

1814 R. Hey in Philos. Trans. (Royal Soc.) 104 375 The centroïd, of an objective circle, is the point represented by the centre of the representing ellipse.

2. With reference to a geometric object or set of points: a point whose coordinates are the means of the corresponding coordinates of all of the points that comprise the object or set. Also: (with respect to a physical body or system of bodies) the point in space coinciding with this.In the case of a set consisting of one or more continuous regions, the coordinates of the centroid are realized as integrals.The centroid of an object having uniform density coincides with its centre of mass.

ΘΚΠ

the world > matter > physics > mechanics > dynamics > statics > [noun] > equal balance of opposing forces > centre of mass or gravity

centre of gravity1633

centre1668

centre of inertia1785

centre of balance1797

centre of mass1842

centroid1844

1844 Mathematician 1 105 The following locus..discloses some elegant properties of the centroïd of a physical or geometrical system.

1882 G. M. Minchin Uniplanar Kinematics 96 To find..the position of the Centroid (‘centre of gravity’) of any plane area.

1942 National Math. Mag. 16 299 In many cases, the student meets these concepts of centroid and moment of inertia for the first time in the course in calculus.

1980 G. Boothroyd & C. Poli Appl. Engin. Mech. v. 71 For bodies of nonuniform density the center of gravity is displaced from the centroid.

2008 J. Stewart Calculus (ed. 6) ix. 579 The centroid of a rectangle is its center.

†3. Chiefly in the work of A. B. W. Kennedy: = centrode n. Obsolete.

ΚΠ

1876 A. B. W. Kennedy tr. F. Reuleaux Kinematics of Machinery ii. 64 The curves..both pass through the whole series of instantaneous centres point by point, and on this account we may call them the centroids [Ger. Polbahnen] of the moving figures. [Note (by Kennedy), p. ix: For the word ‘centroid’..I have to thank Prof. Clifford.]

1884 Athenæum 13 Sept. 339/2 The author erroneously calls the loci of the instantaneous centre ‘centroids’, a term which has become appropriated in a very different sense.

1915 Amer. Machinist 16 Sept. 504/2 The path AB traced by it [sc. the wheel], that is, the ground line, is the centroid of the wheel.

This entry has been updated (OED Third Edition, June 2016; most recently modified version published online December 2021).

单词	centroid
释义	centroidn. Brit. /ˈsɛntrɔɪd/, U.S. /ˈsɛnˌtrɔɪd/ Forms: 1800s– centroïd, 1800s– centroid, 1900s– centeroid. Origin: Formed within English, by derivation. Etymons: centre n.¹, -oid suffix. Etymology: < centre n.¹ + -oid suffix.In later use in sense 3 (in quot. 1876 and later) after cardioid n., cycloid n., and other names of curves; subsequently superseded by centrode n. †1. With reference to a circle represented by an ellipse in the perspective of a given drawing: the point in the interior of the circle that corresponds to the centre of the ellipse. Obsolete. rare. ΚΠ 1814 R. Hey in Philos. Trans. (Royal Soc.) 104 375 The centroïd, of an objective circle, is the point represented by the centre of the representing ellipse. 2. With reference to a geometric object or set of points: a point whose coordinates are the means of the corresponding coordinates of all of the points that comprise the object or set. Also: (with respect to a physical body or system of bodies) the point in space coinciding with this.In the case of a set consisting of one or more continuous regions, the coordinates of the centroid are realized as integrals.The centroid of an object having uniform density coincides with its centre of mass. ΘΚΠ the world > matter > physics > mechanics > dynamics > statics > [noun] > equal balance of opposing forces > centre of mass or gravity centre of gravity1633 centre1668 centre of inertia1785 centre of balance1797 centre of mass1842 centroid1844 1844 Mathematician 1 105 The following locus..discloses some elegant properties of the centroïd of a physical or geometrical system. 1882 G. M. Minchin Uniplanar Kinematics 96 To find..the position of the Centroid (‘centre of gravity’) of any plane area. 1942 National Math. Mag. 16 299 In many cases, the student meets these concepts of centroid and moment of inertia for the first time in the course in calculus. 1980 G. Boothroyd & C. Poli Appl. Engin. Mech. v. 71 For bodies of nonuniform density the center of gravity is displaced from the centroid. 2008 J. Stewart Calculus (ed. 6) ix. 579 The centroid of a rectangle is its center. †3. Chiefly in the work of A. B. W. Kennedy: = centrode n. Obsolete. ΚΠ 1876 A. B. W. Kennedy tr. F. Reuleaux Kinematics of Machinery ii. 64 The curves..both pass through the whole series of instantaneous centres point by point, and on this account we may call them the centroids [Ger. Polbahnen] of the moving figures. [Note (by Kennedy), p. ix: For the word ‘centroid’..I have to thank Prof. Clifford.] 1884 Athenæum 13 Sept. 339/2 The author erroneously calls the loci of the instantaneous centre ‘centroids’, a term which has become appropriated in a very different sense. 1915 Amer. Machinist 16 Sept. 504/2 The path AB traced by it [sc. the wheel], that is, the ground line, is the centroid of the wheel. This entry has been updated (OED Third Edition, June 2016; most recently modified version published online December 2021). < n.1814
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