"A demonstrative is here defined as a grammatical word (or, occasionally, a clitic or affix) which can have pointing (or deictic) reference; for example This is my favourite chair (pointing at an object) or Put it there! (pointing at a place). It could be argued that 1st and 2nd person pronouns have, by their very nature, implicit pointing reference. In view of this, the definition of demonstrative can be modified to be “any item, other than 1st and 2nd person pronouns, which can have pointing (or deictic) reference”." (Dixon 2003)
"Demonstratives are deictic expressions such as English this and that. They indicate the relative distance of a referent in the speech situation vis-à-vis the deictic center. The deictic center, which is also called the origo, is roughly equivalent to the speaker’s location at the time of the utterance." (Diessel 2005)
"For the purposes of this map, a word or affix is considered a demonstrative if it satisfies at least one of two criteria: (1) it has among its uses a meaning that contrasts with some other form in terms of physical proximity to the speaker, so that there is at least a two-way contrast of proximal (near speaker) versus distal (not near speaker); or (2) the form has among its uses an indication that the hearer is intended to direct their attention towards something in the physical environment. In many and probably most languages, demonstratives are associated with both of these functions." (Dryer 2005)
"“My criteria for whether something is a demonstrative is that it have one of two properties: (i) it involves some sort of contrast in spatial distance, usually contrasting proximal with one or more spatial distal categories; or (ii) its basic use is ex- ophoric, referring to something in the shared perceptual space of the speaker and hearer.” (Dryer 2014: e234-e235) ❡
"The term “demonstrative” refers to a small class of expressions that are commonly divided into two basic types: nominal demonstratives such as English this and that and adverbial demonstratives such as here and there (Dixon, 2003). The two types of demonstratives are closely related. They usually include the same deictic roots (Diessel, 1999) and are defined by two basic concepts of language and cognition, i.e., joint attention and deixis (Levinson, 2004; Diessel 2014)." (Diessel & Coventry (2020):