This idiom originally means “a bird startled by the mere twang of a bow-string”. It is now used to describe a badly frightened person (due to past bad experiences).
[otw_shortcode_tabslayout tabs=”2″ tab_1_title=”Simplified Chinese” tab_1_content=”战国时，有一个射箭能手叫「更赢」。他的射箭本领当世无双。有一天，他和魏王走在路上，突然看见有一群鸟从头顶上飞过。
更赢对魏王说：「大王，我可以把天上飞着的鸟射下来吗？」
魏王说：「我知道你是个射箭能手，你不用把它们射下来。」
更赢再说：「我可以不用箭，只要把弓拉一下，就能把鸟打下来。」
魏王很怀疑，问：「射箭能达到这样的功夫？」
正在那时，有一只孤鸟慢慢地飞来。当鸟飞近时，更赢举起弓，拉着弦。鸟飞得越来越近，更赢就把弦放开。随着「咚」的一声直入云霄，正飞着的孤鸟竟然掉了下来。
魏王大吃一惊。他不明白到底是怎么回事。更赢给魏王解释：「那只孤鸟飞得又低又慢，是因为它受过箭伤。因为它飞得慢，它的同伴离它越来越远了。伤口还没愈合，同伴又离了它，它心里很害怕。当它突然听到弓弦声响，他对箭的恐惧使它失去了平衡，就从空中掉了下来。」
后来人们把这故事当成「惊弓之鸟」这个成语。这成语是形容多次受过惊吓的人忽然遇到同样可怕的情况，就惶恐不安，不知道怎么应对。
” tab_2_title=”Traditional Chinese” tab_2_content=”
戰國時，有一個射箭能手叫「更贏」。他的射箭本領當世無雙。有一天，他和魏王走在路上，突然看見有一群鳥從頭頂上飛過。
更贏對魏王說：「大王，我可以把天上飛著的鳥射下來嗎？」
魏王說：「我知道你是個射箭能手，你不用把牠們射下來。」
更贏再說：「我可以不用箭，只要把弓拉一下，就能把鳥打下來。」
魏王很懷疑，問：「射箭能達到這樣的功夫？」
正在那時，有一隻孤鳥慢慢地飛來。當鳥飛近時，更贏舉起弓，拉著弦。鳥飛得越來越近，更贏就把弦放開。隨着「咚」的一聲直入雲霄，正飛著的孤鳥竟然掉了下來。
魏王大吃一驚。他不明白到底是怎麼回事。更贏給魏王解釋：「那隻孤鳥飛得又低又慢，是因爲牠受過箭傷。因爲牠飛得慢，牠的同伴離牠越來越遠了。傷口還沒癒合，同伴又離了牠，牠心裡很害怕。當牠突然聽到弓弦聲響，他對箭的恐懼使牠失去了平衡，就從空中掉了下來。」
後來人們把這故事當成「驚弓之鳥」這個成語。這成語是形容多次受過驚嚇的人忽然遇到同樣可怕的情況，就惶恐不安，不知道怎麼應對。
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English translation:
In the Warring States period, there was an expert archer called “Geng Ying.” His archery skills are unparalleled in his time. One day, he and The King of Wei were on the road and suddenly saw a group of birds flying above their head.
Geng Ying said to The King of Wei: “My king, can I shoot the birds flying in the sky?”
The King of Wei said: “I know that you are an expert in archery, you don’t have to shoot them down.”
Geng Ying spoke again: “I can shoot without using arrows, I just need to pull the bow to shoot the bird down.”
The King of Wei was very suspicious and asked: “Can archery achieve such a skill?”
At that time, there was a lonely bird flying slowly. When the bird flew near, Geng Ying raised the bow and pulled the string. The bird flew closer and closer, and Geng Ying released the bowstring. As the “thump sound” slammed into the sky, the lonely bird that was flying suddenly fell.
The King of Wei was shocked. He didn’t understand what was going on. Geng Ying gave The King of Wei an explanation: “The lonely bird was flying low and slow because it has been injured by an arrow. Because it flew slow, its companion was getting farther and farther away. Its wound had not healed yet, and the companions were leaving, the bird was very scared. When it suddenly heard the bowstring sound, his dread to the arrow made it lose its balance and fell from the air.”
Later, people regarded this story as the idiom “a bird startled by the mere twang of a bow-string”. This idiom means that people who have been frightened many times, when suddenly encountering the same terrible situation, will be frightened and uneasy, and do not know how to deal with it.
The photo is taken from here.