"Flutter" refers to a rapid and often irregular movement or vibration, typically characterized by light, gentle motions. It can refer to the rapid flapping of wings, such as that of a bird or butterfly, or the quivering motion of leaves in the wind. "Flutter" can also describe a state of excitement, nervousness, or anticipation that creates a feeling of mild agitation or restlessness. Additionally, in engineering or aerodynamics, "flutter" pertains to a potentially harmful vibration or oscillation of structures, like aircraft wings, caused by aerodynamic forces. The term encompasses various contexts where quick, delicate movements or sensations are involved.