focal length

noun

Definition of focal length

  1. :  the distance of a focus from the surface of a lens or curved mirror

First Known Use of focal length

1682


FOCAL LENGTH Defined for English Language Learners

focal length

noun

Definition of focal length for English Language Learners

  • : the distance from the surface of a lens to the point of focus (sense 3)


Medical Dictionary

focal length

play
noun \-ˌleŋ(k)th\

Medical Definition of focal length

  1. :  the distance of a focus from the surface of a lens or concave mirror—symbol f


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