Declensions refer to the different forms a word can take to indicate its grammatical function. Some synonyms for declensions include grammatical inflections, verb conjugations, noun declinations, and adjective declinations. These terms are all used to describe the process of changing the ending of words to indicate tense, case, gender, or number. Other related concepts include morphemes, which are the smallest units of meaning in language, and syntax, which refers to the rules for combining words into phrases and sentences. Knowing these synonyms and related concepts can be helpful when learning a new language or studying linguistic theories.