Interlanguage refers to the language system developed by a learner as they acquire a second language. Other synonyms for interlanguage include learner language, developing language, transitional language, and approximative system. These terms describe a language in progress, which may contain elements from the learner's native language as well as features from the target language. Similarly, pidgin and creole are also related terms that describe developing languages formed from a blend of two or more existing languages. While these terms are all related, they each have specific connotations and uses in different linguistic contexts, highlighting the nuanced nature of language acquisition and development.