The character 哀in Chinese language is frequently used in daily life. Generally speaking, the most frequently used meaning of it should be sad or grieve . The words you often use when you go to school to study in China may be 悲哀. Another meaning common meaning is to mourn in the words such as 哀悼and默哀. Sometimes, it is applied to mean to show compassion for somebody like哀其不幸. Of course, it could be the surname of a Chinese family.
After knowing the basic meanings of this character, the following parts will focus on some important and popular words formed by 哀. The set phrase 哀兵必胜is a word you should understand which originated from one sentence in the book Lao Zi, reading 故抗兵相若，则哀者胜矣, meaning that if two armies with the similar power are fighting, it is more possible that the side with grief and indignation will win. Accordingly, this phrase indicates the army fights because of being constrained will win the war.
When mentioning about describing the war, 哀鸿遍野is a vivid set phrase which is applied to imply the victims without houses are groaning everywhere. If you study Mandarin online, you should know the word哀悼we just mentioned means to show condolence sorrowfully to the dead like 哀悼死难烈士and表示沉痛的哀悼. In the two sentences, 哀悼in the former sentence is a verb while that in the latter functions as a noun. 哀求carries the meaning of requesting entreatingly.
As a matter of fact, many sorrowful things can be described by 哀. For some examples, 哀辞means the article written to mourn the dead, which can be also called 哀启. 哀歌 is the mournful song while哀思is a kind of grieve affection. 哀乐is the sad music which is especially used for funeral or mourning memorial. If you hear people say 喜怒哀乐during the period when you come to learn Chinese language in China, you should know it means the four passions like pleasure, anger, sorrow and joy. Therefore, it is often used to express people’s all feelings in general.