Foci [noun]
Definition of Foci:
center of attraction
Sentence/Example of Foci:
In an orbit made elliptical by the planetary attraction the sun necessarily occupies one of the foci of the ellipse.
That an ellipse may be given any required proportion of width to length by locating the foci at the requisite distance apart.
That the proportion of length to width in an ellipse is determined by the distance apart of the foci.
The curve thus traced will be an ellipse having the pins at the two points which are called its foci.
These are at points on the principal axis that are twice as far from O, the center of the lens, as are the principal foci.
Two ellipsoids in which the principal sections lie in the same planes, and have the same foci, are called confocal.
In barbarous places, the legions that were intended as garrisons proved to be foci of civilization.
Their physicians were their great philosophers; their medical colleges were their foci of learning.
Foci of pus occur throughout the gland, causing destruction of the tissue, so that the gland may become a single abscess cavity.
With the Williamson camera focussing is unnecessary within certain distances owing to the fixed foci of the stops.