Morpheme
Changing definitions

In generative grammar, the definition of a morpheme depends heavily on whether syntactic trees have morphemes as leaves or features as leaves.

Given the definition of a morpheme as "the smallest meaningful unit", nanosyntax aims to account for idioms in which an entire syntactic tree often contributes "the smallest meaningful unit". An example idiom is "Don't let the cat out of the bag". There, the idiom is composed of "let the cat out of the bag". That might be considered a semantic morpheme, which is itself composed of many syntactic morphemes. Other cases of the "smallest meaningful unit" being longer than a word include some collocations such as "in view of" and "business intelligence" in which the words, when together, have a specific meaning.

The definition of morphemes also plays a significant role in the interfaces of generative grammar in the following theoretical constructs:
detectable_format:number_bullet_lists[3], oulipo:avoid_letter[t], language:response_language[Latin]