Editing Idiom (section)

== Mobility ==
Idioms possess varying degrees of mobility. Whereas some idioms are used only in a routine form, others can undergo syntactic modifications such as passivization, raising constructions, and [[clefting]], demonstrating separable constituencies within the idiom.<ref name=":0">{{Cite journal|last=Horn|first=George|year=2003|title=Idioms, Metaphors, and Syntactic Mobility|journal=Journal of Linguistics|volume=39|issue=2 |pages=245–273|doi=10.1017/s0022226703002020}}</ref> ''Mobile idioms'', allowing such movement, maintain their idiomatic meaning where ''fixed idioms'' do not:
;Mobile: ''I spilled the beans on our project.'' → ''The beans were spilled on our project.'' (valid)
;Fixed: ''The old man kicked the bucket.'' → *''The bucket was kicked'' (by the old man). (confusing)
Many fixed idioms lack ''semantic composition'', meaning that the idiom contains the semantic role of a verb, but not of any object. This is true of ''kick the bucket'', which means ''die''. By contrast, the semantically composite idiom ''spill the beans'', meaning ''reveal a secret'', contains both a semantic verb and object, ''reveal'' and ''secret''. Semantically composite idioms have a syntactic similarity between their surface and semantic forms.<ref name=":0" />

The types of movement allowed for certain idioms also relate to the degree to which the literal reading of the idiom has a connection to its idiomatic meaning. This is referred to as ''motivation'' or ''transparency''. While most idioms that do not display semantic composition generally do not allow non-adjectival modification, those that are also motivated allow lexical substitution.<ref>{{Cite journal|last=Keizer|first=Evelien|year=2016|title=Idiomatic expressions in Functional Discourse Grammar|journal=Linguistics|volume=54|issue=5 |pages=981–1016|doi=10.1515/ling-2016-0022|s2cid=151574119 }}</ref> For example, ''oil the wheels'' and ''grease the wheels'' allow variation for nouns that elicit a similar literal meaning.<ref>{{Cite journal|last=Mostafa|first=Massrura|year=2010|title=Variation in V+the+N idioms|journal=English Today|volume=26|issue=4 |pages=37–43|doi=10.1017/s0266078410000325|s2cid=145266570 }}</ref> These types of changes can occur only when speakers can easily recognize a connection between what the idiom is meant to express and its literal meaning, thus an idiom like ''kick the bucket'' cannot occur as ''kick the pot''.

From the perspective of [[dependency grammar]], idioms are represented as a [[catena (linguistics)|catena]] which cannot be interrupted by non-idiomatic content. Although syntactic modifications introduce disruptions to the idiomatic structure, this continuity is only required for idioms as lexical entries.<ref>{{Cite journal|last=O'Grady|first=William|year=1998|title=The Syntax of Idioms|journal=Natural Language and Linguistic Theory|volume=16|issue=2 |pages=279–312|doi=10.1023/a:1005932710202|s2cid=170903210 }}</ref>

Certain idioms, allowing unrestricted syntactic modification, can be said to be metaphors. Expressions such as ''jump on the bandwagon'', ''pull strings'', and ''draw the line'' all represent their meaning independently in their verbs and objects, making them compositional. In the idiom ''jump on the bandwagon'', ''jump on'' involves joining something and a 'bandwagon' can refer to a collective cause, regardless of context.<ref name=":0" />