Noun

(es)

An object, usually made of glass, that focuses or defocuses the light that passes through it.

* {{quote-magazine, year=2013, month=July-August, author= Catherine Clabby

, magazine=(American Scientist), title= Focus on Everything , passage=Not long ago, it was difficult to produce photographs of tiny creatures with every part in focus. That’s because the lenses that are excellent at magnifying tiny subjects produce a narrow depth of field.}}

A device which focuses or defocuses electron beams.

(geometry) A convex shape bounded by two circular arcs, joined at their endpoints, the corresponding concave shape being a lune.

(biology) A genus of the legume family; its bean.

(anatomy) The transparent crystalline structure in the eye.

* {{quote-magazine, year=2013, month=July-August, author= Fenella Saunders, magazine=(American Scientist)

, title= Tiny Lenses See the Big Picture , passage=The single-imaging optic of the mammalian eye offers some distinct visual advantages. Such lenses can take in photons from a wide range of angles, increasing light sensitivity. They also have high spatial resolution, resolving incoming images in minute detail.}}

(by extension, figuratively) A way of looking, literally or figuratively, at something.

* 2004 April 11, Ann Hulbert, "Are the Kids All Right?", in (The New York Times Magazine) , page 11:

If "the public looks at the condition of America's children largely through a negative lens ," worries Child Trends promote child well-being."

Noun

(en noun)

A non-existent or empty value or set of values.

Zero]] quantity of [[expression, expressions; nothing.

(Francis Bacon)

Something that has no force or meaning.

(computing) the ASCII or Unicode character (), represented by a zero value, that indicates no character and is sometimes used as a string terminator.

(computing) the attribute of an entity that has no valid value.

Since no date of birth was entered for the patient, his age is null .

One of the beads in nulled work.

(statistics) null hypothesis