Editing Tilde (section)

===Linguistics===
The tilde may indicate alternating [[allomorph]]s or [[Morphophonology|morphological alternation]], as in {{IPA|//ˈniː~ɛl+t//}} for ''kneel~knelt'' (the [[plus sign#Other uses|plus sign]] '+' indicates a morpheme boundary).<ref>Collinge (2002) ''An Encyclopedia of Language'', §4.2.</ref><ref>{{Cite book | last=Hayes | first=Bruce | author-link=Bruce Hayes (linguist) | title=Introductory Phonology | publisher=John Wiley & Sons | date=2011 | isbn=9781444360134 | pages=87–88 }}</ref>

The tilde may represent some sort of phonetic or phonemic variation between two sounds, which might be [[allophone]]s or in [[free variation]]. For example, {{IPA|[χ ~ x]}} can represent "either {{IPA|[χ]}} or {{IPA|[x]}}".

In [[formal semantics (linguistics)|formal semantics]], it is also used as a notation for the ''[[squiggle operator]]'' which plays a key role in many theories of [[focus (linguistics)|focus]].<ref>{{cite book |last=Buring |first=Daniel |date=2016 |title=Intonation and Meaning |doi=10.1093/acprof:oso/9780199226269.003.0003 |publisher=Oxford University Press |pages=36–41 |isbn=978-0-19-922627-6}}</ref>

In [[interlinear gloss]], a tilde sets off an element added to a word by [[reduplication]]; were a hyphen or double hyphen used instead, confusion would arise because that element would be notated  in the same way as an independent morpheme requiring an independent gloss.