na-adjective, noun
highest honors; summa cum laude
Used in academic contexts for the highest level of distinction, equivalent to summa cum laude. Often appears in formal descriptions of graduation honors.
彼は大学を最優等で卒業した。
He graduated from university with highest honors.
最優等の成績を収めた学生が表彰された。
Students who achieved the highest distinction were recognized.
首席 refers to the top-ranking student (valedictorian), whereas 最優等 is a grade-based distinction (summa cum laude) that may be awarded to multiple students.
Compound of 最 (sai, 'most') + 優等 (yūtō, 'honors, distinction'). The term is a direct calque of Western academic Latin honors terminology.