The bound phrase 'bound phrase' has been in my lexicon (and thus "a thing" for me) since long before I encountered it in its library-search sense (in which putting quotation marks around a search string should restrict the results to occurrences of exactly that string, though Google seems iffy about that in the current AI-polluted version). MY sense of 'bound phrase' seems to come from linguistics/philology, and valorizes the mysterious forces that operate between the component lexemes. Thus,
is greater [more nuanced] than the simple sum of 'world' + 'model'.
Among the terms that seem to be trying to cover [parts of] the same semantic territory:
...The "newish branch of lexicography known as phraseology... loosely defined as 'the study of conventional phrases" (Aitchison 115)
what you learn in library school, what's in a name Jessamyn at librarian.net
...Google's gotten us all pretty comfortable with just tossing a hash of basically-accurate letters into a search box and having it come back with more or less what you're looking for. Using other, generally worse, search engines can often require doing things like "bound phrase" searching (see what I did there?) where the only way you're going to come back with anything remotely accurate is to say that you're looking for a bunch of specific words in a specific order.
Phraseme Wikipedia
Phraseme Semanticscholar.org
also called a set of thoughts, set phrase, idiomatic phrase, multi-word expression, or idiom, is a multi-word or multi-morphemic utterance at least one of whose components is [not?] selectionally constrained or restricted by linguistic convention such that it is freely chosen.
Phrasemes omniglot.com
...One type of phraseme is idioms, such as to hit the sack (to go to sleep), under the weather (sick, unwell). Idioms are also known as non-compositional phrasemes, as their meanings cannot be determined from the meanings of their component words.Another example is the compositional phraseme, which consists of words that normally appear together, such as heavy rain, strong wind and bright sun (you wouldn't usually say heavy wind.)
(Much of the scholarship in phraseology seems to be Eastern European, which is to say carried on by non-native speakers of English)
Morphemic and Syntactic Phrasemes Igor Mel'cuk Yearbook of Phraseology (2021) (pdf)
Phraseology in the language, in the dictionary, and in the computer Igor Mel'cuk (2012)
Cognitive-Semiotic Mechanisms of Phraseme Building Nikolay Fedorovich Alefrenko
Cognitive-semiotic mechanisms of phraseme semiosis is perhaps the least researched area of phraseology and cognitive linguistics that is explained by the complex comprehensible nature of phraseme in terms of codetermination of indirect nomination and cognition