In a court, the complainant is the person who starts things by making a formal complaint: they say, in the official way, that someone has wronged them and they want the law to look at it.

In a court在法庭上, the complainant告訴人 is是 the person who starts things by making a formal complaint那個正式提出申訴、率先採取行動的人: they say, in the official way,他們正式地說 that someone has wronged them有人對他們做了不對的事 and they want the law to look at it並希望法律介入處理.

It is legal English, not kitchen-table English. A neighbour who grumbles about noise is not a complainant unless they have actually gone to the police, a government office, or the court.

It is它是 legal English法律英語, not kitchen-table English不是日常口語. A neighbour who grumbles about noise一個抱怨噪音的鄰居 is not a complainant並不算是告訴人 unless除非 they have actually gone to他們真的去過 the police, a government office, or the court警察局、政府機關或法院.

In a criminal case this is often the person who reports the harm; in some civil cases it is another name for the person bringing the claim. Lawyers, judges, and news reports about trials use it.

In a criminal case在刑事案件裡 this is often這通常是 the person who reports the harm通報受害情況的人; in some civil cases在某些民事案件裡 it is another name for它是另一種說法, for the person bringing the claim指提出訴訟的人. Lawyers, judges, and news reports about trials律師、法官和報導審判的新聞 use it都會用這個詞.

The everyday verb complain is much wider — you can complain about food, weather, homework. This noun is narrower and more official: it names a role in a case.

The everyday verb complain日常動詞 complain is much wider範圍廣得多 — you can complain about你可以抱怨 food, weather, homework食物、天氣、作業. This noun這個名詞 is narrower and more official範圍較窄也較正式: it names a role in a case它指的是案件裡的一個角色.