Floaters are deposits of various size, shape, consistency, refractive index, and motility within the eye's normally transparent vitreous humour. They may be of embryonic origin or acquired due to degenerative changes of the vitreous humour or retina. The perception of floaters is known as myodesopsia, or less commonly as myiodeopsia, myiodesopsia, or myodeopsia. When observed subjectively, floaters are entoptic phenomena characterized by shadow-like shapes that appear singly or together with several others in one's field of vision. They may appear as spots, threads, or fragments of cobwebs, which float slowly before one's eyes.
Latin-derived Muscae volitantes (meaning 'flying flies'), or French-derived mouches volantes, are a specific type of floater consisting of small spots whose presence is normal and attributed to minute remnants of embryonic structures in the vitreous humour.