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focus

n. · v.
US //ˈfoʊkəs// UK //fˈəʊkəs// fo·cus
  1. 1 attention (n.)
    A2 Elementary

    the main thing that people are paying attention to.

    the central point of attention, activity, or interest. Often used with 'of' to indicate the subject.

    Example

    The main focus of the meeting was how to save money this year.

    Example

    The primary focus of the research shifted from urban development to the environmental impact of suburban sprawl over the last decade.
  2. 2 clear image (n.)
    B1 Intermediate Photography

    the state of an image being sharp and clear, especially in a photo.

    the state of maximum clarity of an image, achieved when light rays converge correctly on a surface.

    Example

    The background of the photo is blurry, but the flower is in focus.

    Example

    The photographer struggled to maintain focus on the moving subject while using a wide aperture in low-light conditions.
    • blurriness
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  1. 3 active window (n.)
    C1 Advanced Technical Computing

    the part of a computer screen that is currently active or selected.

    the status of being the currently active element in a user interface, typically receiving keyboard or mouse input.

    Example

    Click on the text box to give it focus so you can start typing.

    Example

    The application failed to return focus to the main window after the dialogue box was dismissed, frustrating the user.
  2. 4 to concentrate (v.)
    A2 Elementary

    to give all your attention to one particular thing.

    to direct one's attention, effort, or energy toward a specific task or subject. Intransitive uses typically require the preposition 'on'.

    Example

    It is hard to focus on my work when the room is so noisy.

    Example

    The marketing team decided to focus on digital platforms rather than traditional print media to reach a younger demographic.

    Usage

    Usually takes the preposition 'on'.
    Pitfall
    I need to focus in my homework.
    I need to focus on my homework.

    The verb focus always takes the preposition 'on' when followed by an object.

  3. 5 to adjust a lens (v.)
    B1 Intermediate Photography

    to move a lens so that you can see an image clearly.

    to adjust the focal length of an optical device to produce a sharp image.

    Example

    He turned the ring on the camera to focus on the bird in the tree.

    Example

    Modern autofocus systems can focus on a subject's eyes almost instantly, even when the person is moving through the frame.
Origin

Borrowed from Latin focus (“hearth, fireplace”); see there for more. Related to fuel. Kepler introduced the term into mathematics and the sciences in describing elliptical orbits of planets (quote from Nicholas Mee) : "One of the interesting properties of an ellipse is that if there were a light bulb at one focus, then all the light that it emits would reflect off the ellipse and converge at the other focus. This is why Kepler originally used the name focus for these points."

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