Mathematics The limit that a function ƒ is said to approach at x = a when ƒ(x) is larger than any preassigned number for all x sufficiently near a.
A range in relation to an optical system, such as a camera lens, representing distances great enough that light rays reflected from objects within the range may be regarded as parallel.
A distance setting, as on a camera, beyond which the entire field is in focus.
c.1374, from O.Fr. infinité, from L. infinitatem (nom. infinitas) "boundlessness," from infinitus boundless, unlimited" (see infinite). Infinitas used as a loan-transl. of Gk. apeiria "infinity," from apeiros "endless."
infinity 1. The size of something infinite. Using the word in the context of sets is sloppy, since different infinite sets aren't necessarily the same size cardinality as each other. See also aleph 0 2. The largest value that can be represented in a particular type of variable (register, memory location, data type, whatever). See also minus infinity. [The Jargon File] (1994-11-18)
In*fin"i*ty\, n.; pl. Infinities. [L. infinitas; pref. in- not + finis boundary, limit, end: cf. F. infinit['e]. See Finite.]1. Unlimited extent of time, space, or quantity; eternity; boundlessness; immensity. --Sir T. More. There can not be more infinities than one; for one of them would limit the other. --Sir W. Raleigh. 2. Unlimited capacity, energy, excellence, or knowledge; as, the infinity of God and his perfections. --Hooker. 3. Endless or indefinite number; great multitude; as an infinity of beauties. --Broome. 4. (Math.) A quantity greater than any assignable quantity of the same kind. Note: Mathematically considered, infinity is always a limit of a variable quantity, resulting from a particular supposition made upon the varying element which enters it. --Davies & Peck (Math. Dict.). 5. (Geom.) That part of a line, or of a plane, or of space, which is infinitely distant. In modern geometry, parallel lines or planes are sometimes treated as lines or planes meeting at infinity. Circle at infinity, an imaginary circle at infinity, through which, in geometry of three dimensions, every sphere is imagined to pass. Circular points at infinity. See under Circular.
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