synonym

synonym
/ˈsɪnənɪm; `sɪnəˌnɪm/ n
word or phrase with the same meaning as another in the same language, though perhaps with a different style, grammar or technical use 同义词; 同义词组; 同义语
    `Slay' and `kill' are synonyms. slay 和 kill 是同义词.

牛津英汉双解词典