repeated movement from one position to another

The oscillations of the needle were so slight they were hard to detect. 指针的摆动非常轻微，很难察觉。

repeated change from one feeling or opinion to another

His mood never settled; there was a continuous oscillation between two extremes. 他的心情从未安定下来; 总是在两个极端之间摇摆不定。

a regular change in strength or direction in a wave or electric current

Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas. 声音是一种机械波，是通过固体、液体或气体传播的压力振荡。