1.
auxiliary verb
A grammatical term for verbs or verb-like elements that attach to other words to add meaning such as tense, negation, politeness, or modality. In Japanese grammar, this category includes elements like ます, ない, た, れる, and られる.
Usage
助動詞 is a technical grammar term used in Japanese language education. In traditional Japanese grammar (国文法), the category of 助動詞 is broader than the English concept of "auxiliary verb" and includes elements that express negation (ない), past tense (た), politeness (ます), passive (れる/られる), and more.
Watch out
In English grammar, auxiliary verbs are words like "can," "will," and "have." Japanese 助動詞 are mostly endings attached to verbs and other words, not independent words.