Combinatorial complexity refers to the vast number of ways in which elements (like words or phrases) can be combined to create new structures or meanings. In the context of language, this complexity allows for the generation of unusual yet possible sentences through several mechanisms:

1. Word Combinations: The English language, for example, has a finite set of words, but the combinations of these words can be virtually infinite. By rearranging words or using them in novel contexts, we can create sentences that are grammatically correct but may not be commonly used or expected.

2. Syntax Variability: Different syntactic structures can lead to unusual sentences. For instance, changing the order of subjects, verbs, and objects can yield sentences that are grammatically correct but semantically surprising. For example, "The cat chased the mouse" can be transformed into "The mouse was chased by the cat," which conveys the same meaning but in a different structure.

3. Metaphor and Simile: Combinatorial complexity allows for the use of figurative language, where words are combined in ways that evoke new meanings. For example, saying "Time is a thief" combines the concepts of time and theft in a way that creates a vivid image, even though it is not literally true.

4. Neologisms and Portmanteaus: Language is dynamic, and new words can be created by combining existing ones. For example, "brunch" (breakfast + lunch) is a neologism that describes a meal that combines elements of both. Such combinations can lead to unusual yet meaningful expressions.

5. Contextual Flexibility: The meaning of a sentence can change dramatically based on context. A sentence like "I saw the man with the telescope" can be interpreted in multiple ways depending on who is perceived as having the telescope, showcasing how combinatorial complexity interacts with context to create ambiguity and novelty.

6. Creative Writing and Poetry: Writers often exploit combinatorial complexity to create unique expressions. Poets, for instance, may use unexpected word pairings or structures to evoke emotions or imagery that challenge conventional thought.

In summary, combinatorial complexity in language allows for the creation of unusual yet possible sentences by enabling diverse word combinations, flexible syntax, figurative language, and creative expression. This complexity is a fundamental aspect of linguistic creativity and communication.