adj.无原因的；无理由的；无缘无故的；偶然的

The laughter that erupted in the room was causeless, a spontaneous expression of joy.
房间里爆发出的笑声是无缘无故的，是喜悦的自然流露。
Her mood swings seemed causeless, leaving her friends puzzled and concerned.
她的情绪波动似乎没有缘由，让朋友们感到困惑和担忧。
Some days the stock market fluctuates causelessly, reacting to no apparent news or events.
有些时候，股市无缘无故地波动，对任何明显的新闻或事件都没有反应。
The sudden rainstorm appeared causeless, catching everyone off guard without any warning signs.
突如其来的大雨似乎是无缘无故的，没有任何预兆，让所有人都措手不及。
His generosity was often causeless, showering gifts on friends and strangers alike just because he could.
他的慷慨常常是没有缘由的，仅仅因为他能这样做，就对朋友和陌生人施以馈赠。
The dog barked incessantly at midnight, disturbing the neighborhood for what seemed like a causeless reason.
那只狗在午夜不停地吠叫，无缘无故地打扰了整个社区的安宁。
Her smile illuminated the room, a causeless beacon of happiness that drew people towards her.
她的微笑照亮了整个房间，像是无缘无故的幸福灯塔，吸引着人们向她靠近。
The sudden change in his attitude was causeless, leaving colleagues wondering what had triggered it.
他态度的突然转变没有明显原因，这让同事们都在猜测是什么触发了这一变化。
causeless panic can sometimes grip a crowd, leading to chaotic scenes where everyone is trying to flee without knowing why.
无缘无故的恐慌有时会控制住人群，导致混乱的场面，每个人都试图逃离，却不知道为什么。
Her decision to quit her job seemed causeless, but deep down she knew it was time for a change.
她辞职的决定看似没有理由，但在内心深处，她知道自己是时候做出改变了。