focus

noun (plural focuses or foci 'fəʊsʌɪ)

1》 the centre of interest or activity.

    ↘an act of focusing on something.

2》 the state or quality of having or producing clear visual definition.

    ↘another term for focal point.

    ↘the point at which an object must be situated with respect to a lens or mirror for an image of it to be well defined.

3》 Geology the point of origin of an earthquake. Compare with epicentre.

4》 Medicine the principal site of an infection or other disease.

5》 Geometry one of the fixed points from which the distances to any point of an ellipse, parabola, or other curve are connected by a linear relation.

6》 Linguistics an element of a sentence that is given prominence by intonational or other means.

verb (focuses, focusing, focused or focusses, focussing, focussed)

1》 adapt to the prevailing level of light and become able to see clearly.

    ↘adjust the focus of (a telescope, camera, etc.).

    ↘(of rays or waves) meet at a single point.

    ↘(of light, radio waves, or other energy) become concentrated into a sharp beam of light or energy.

2》 (focus on) pay particular attention to.

3》 Linguistics place the focus on (a part of a sentence).

Derivatives

focuser noun

Origin

C17: from L., lit. 'domestic hearth'.