Tak bym to ujął. Nie wiem, czy już istnieje jednowyrazowe tłumaczenie.

- student ostatniego roku, wygłaszający przemówienie na uroczystości rozdania dyplomów;
- student ostatniego roku (zwykle jeden z prymusów), otwierający uroczystość wręczenia dyplomów
https://ling.pl/slownik/angielsko-polski/salutatorian

salutatorian: the student usually having the second highest rank in a graduating class who delivers the salutatory address at the commencement exercises
https://www.merriam-webster.com/dictionary/salutatorian

a person, usually the student with the second highest academic achievement, who delivers a speech of greeting at a graduation ceremony
https://www.thefreedictionary.com/salutatorian

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A salutatorian is a graduate who finished with the second highest rank in his or her class. Only the valedictorian did better.

Being the salutatorian of your graduating class is a great honor. Traditionally, the salutatorian gives the opening remarks at the graduation ceremony. So, just as a salutation is a greeting, a salutatorian is responsible for offering a formal greeting at the event. Having been a salutatorian looks great on a resume, as long as you spell it correctly.
https://www.vocabulary.com/dictionary/salutatorian

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Valedictorian vs. Salutatorian: What's the Difference?

Most schools award the title of valedictorian to the student who graduates with the highest cumulative GPA. ...
valedictorians are usually named during the second semester of senior year, and the award comes with a few special perks. First, the valedictorian usually gets special graduation regalia (also known as graduation attire) to help them stand out from the crowd. This can be a different colored robe, a unique tassel on your mortarboard, or an additional stole, cord, or medal. Each school has a unique set of regalia, but you’ll definitely get some additional swag for your hard work. ...
the valedictorian plays an important role in the graduation ceremony. Unlike most graduates, who will only come on stage to get their diploma, valedictorians usually sit on stage and actually participate in the ceremony itself by giving a speech.

Traditionally, the title of salutatorian is given to the second highest-ranking student in a graduating class. Just like the valedictorian, this is determined by a student’s cumulative, weighted GPA....
Like the valedictorian, the salutatorian often gets special graduation regalia to recognize their achievement. These are usually similar to the valedictorian regalia with minor adjustments....
Additionally, the salutatorian also plays a pivotal role in the graduation ceremony. Like the valedictorian, the salutatorian is tasked with delivering a speech on stage during the ceremony itself. The salutatorian’s speech serves a different purpose than the valedictorian’s speech—which we’ll talk about in the next section!—but it also serves as a special reward for the salutatorian’s hard work.
https://blog.prepscholar.com/valedictorian-vs-salutatorian

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absolwent ostatniego roku (jeden z prymusów/z drugim wynikiem), otwierający uroczystość wręczenia dyplomów

Proponuję zmianę studenta na absolwenta, ponieważ chodzi tu o szkołę średnią, a nie o studia.

Salutatorian osiągnął drugi wynik ocen w szkole za valedictorian (najlepszy wynik). Salutatorian tradycyjnie wygłasza oficjalną mowę otwierającą na ceremonii rozdania dyplomów absolwentom. Inną przemowę wygłasza w trakcie ceremonii valedictorian.

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Ostateczna wersja taka: absolwent z drugim wynikiem otwierający uroczystość wręczenia dyplomów

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lub -> uczeń z drugim wynikiem otwierający uroczystość wręczenia dyplomów

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Valedictorian / Salutatorian - tytuły używane zarówno w szkole średniej jak i na studiach

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Valedictorian - pochodzi z łaciny od vale dicere ("to say farewell")
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Salutatorian - 1841, American English, from salutatory "of the nature of a salutation," here in the specific sense "designating the welcoming address given at a college commencement" (1702) + -ian. The address was originally usually in Latin and given by the second-ranking graduating student.
https://www.etymonline.com/word/salutatorian

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Kolejne źródło:
salutatorian - absolwent otwierający uroczystość wręczenia dyplomów, osiągający drugi najwyższy wynik
https://quizlet.com/pl/469839989/presentations-vocabulary-fl...

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wyróżniony jako drugi najlepszy absolwent roku

Ukończył Princeton w roku 1993, otrzymał wyróżnienie jako drugi najlepszy absolwent roku.
Professor Burnett graduated from Princeton in 1993 as the salutatorian.
https://issuu.com/beczmiana/docs/ekspektatywa4_gry_losowe