Unnumbered source etymology
Original entry ↗A point at which reflected or refracted rays of light converge. · A point of a conic at which rays reflected from a curve or surface converge. · The fact of the convergence of light on the photographic medium. · The quality of the convergence of light on the photographic medium.
To cause (rays of light, etc) to converge at a single point. · To adjust (a lens, an optical instrument) in order to position an image with respect to the focal plane. · To adjust itself or be adjusted such that light from a scene converges appropriately to create a clear image. · To direct attention, effort, or energy to a particular audience or task.
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."
Relationships mentioned by the source
These are extracted mentions, not a timeline or a verified sequence of immediate parents.
- Borrowed-form mentionfocusla
This page abbreviates 11 auxiliary source items. The etymology narrative is not shortened. Omission counts are available in the audit fields below; consult the original for complete auxiliary material.
Inspect preserved source fields
Raw extraction fields are retained for auditing. Their order does not establish ancestry.
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