# infinity

Pronunciation: US say "in-FIN-i-tee" /ɪnˈfɪnɪti/; UK

## Noun

1. The state or quality of being endless and unlimited, with no beginning, no end, and no limit to size.
   - Simple: The state of having no start, no end, and no limit to how big something is.
   - _Philosophers have long argued over whether the universe extends to infinity or ends somewhere._
   - _Her novel tries to convey the infinity of time, which has no first moment and no last._
2. In mathematics, a number with an infinite value, one that cannot be counted.
   - Simple: In math, a number that is endless in value and can never be counted.
   - _Physicists spent years learning to tame the infinities that appeared whenever they calculated the electron's self-energy._
   - _Under standard floating-point rules, dividing a positive number by zero produces positive infinity._
3. The written sign ∞, shaped like a figure eight lying on its side.
   - Simple: The sign ∞, which looks like the number 8 lying on its side.
   - _In the formula, a small infinity sits above the summation sign._
   - _The jeweler engraved an infinity between the couple's initials on the inside of the ring._
4. In analysis and topology, an idealized point that sequences of values are said to approach when their magnitudes increase without bound.
   - Simple: In math, an imagined point that a list of numbers gets closer to as their size grows without end.
   - _As n tends to infinity, the partial sums of 1 + 1/2 + 1/4 + … approach 2._
   - _In projective geometry, two parallel lines meet at a single point at infinity._
5. A number so large compared with some characteristic number of a problem that, for practical purposes, it can be treated as infinite.
   - Simple: A number so much bigger than some key number that it can be treated as endless.
   - _For the landscape shots, she set the lens to infinity so the distant ridgeline would be sharp._
   - _Because the source is hundreds of focal lengths away, we can place it at infinity and treat the incoming rays as parallel._

## Origin

From Middle English infinite, from Old French infinité, from Latin īnfīnitās ("unlimitedness"). The Latin word combines the negative prefix in- ("not"), fīnis ("end"), and the noun-of-state suffix -tās.

Source: DictionaryAI, https://dictionaryai.com/define/infinity (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).