also: クェスチョンマーク · クエッションマーク
noun
The punctuation mark '?' used in writing to indicate a question. Also used figuratively for something uncertain or unresolved.
See also: 疑問符
文の終わりにクエスチョンマークを付けてください。
Please put a question mark at the end of the sentence.
彼の返事
His answer is still a question mark.