This is the 1607th most frequent Japanese word.
抗議
Protest; objection.
Here, "抗議" is used to mean a formal or organized expression of disagreement or objection to the actions or decisions of someone, specifically the principal here.
学生たちは校長に抗議の手紙を送った。
The students sent a protest letter to the principal.
In this sentence, "抗議" refers to a person's act of expressing objection or opposition, often accompanied by strong emotions, shown here as anger.
彼は怒りを込めて抗議した。
He protested vehemently in anger.
The word "抗議" in this context is used to represent collective or public dissent and vocal opposition towards a societal or governmental action, here a new law.