A window is a transparent or translucent opening in a wall or door that allows the passage of light and, if not closed or sealed, air and sound. Windows are usually glazed or covered in some other transparent or translucent material like float glass. Windows are held in place by frames, which prevent them from collapsing in. Many glazed windows may be opened, to allow ventilation, or closed, to exclude inclement weather.

The word window originates from the Old Norse ‘vindauga’, from ‘vindr – wind’ and ‘auga – eye’, i.e. "wind eye". In Norwegian Nynorsk and Icelandic the Old Norse form has survived to this day (in Icelandic only as a less used synonym to gluggi), in Swedish the word vindöga remains as a term for a hole through the roof of a hut, and in the Danish language ‘vindue’ and Norwegian Bokmål ‘vindu’, the direct link to ‘eye’ is lost, just like for 'window'. The Danish (but not the Bokmål) word is pronounced fairly similarly to window.

Window is first recorded in the early 13th century, and originally referred to an unglazed hole in a roof. Window replaced the Old English ‘eagþyrl’, which literally means ‘eye-hole,’ and ‘eagduru’ ‘eye-door’. Many Germanic languages however adopted the Latin word ‘fenestra’ to describe a window with glass, such as standard Swedish ‘fönster’, or German ‘Fenster’. The use of window in English is probably due to the Scandinavian influence on the English language by means of loanwords during the Viking Age. In English the word fenester was used as a parallel until the mid-18th century and fenestration is still used to describe the arrangement of windows within a façade.

Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement. In higher organisms the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods.

The simplest "eyes", such as those in microorganisms, do nothing but detect whether the surroundings are light or dark, which is sufficient for the entrainment of circadian rhythms.^{[citation needed]} From more complex eyes, retinal photosensitive ganglion cells send signals along the retinohypothalamic tract to the suprachiasmatic nuclei to effect circadian adjustment.

The word asshole, a variant of arsehole, which is still prevalent in British and Australian English, is a vulgar to describe the anus, often pejoratively used to refer to people.

The word arse in English derives from the Germanic root *arsaz, which originated from the Proto-Indo-European root *ors — meaning buttocks or backside. The combined form arsehole is first attested from 1500 in its literal use to refer to the anus. The metaphorical use of the word to refer to the worst place in a region, e.g., "the arsehole of the world") is first attested in print in 1865; the use to refer to a contemptible person is first attested in 1933. In the ninth chapter of his 1945 autobiography, Black Boy, Richard Wright quotes a snippet of verse that uses the term: "All these white folks dressed so fine / Their ass-holes smell just like mine ...". Its first appearance as an insult term in a newspaper indexed by Google News is in 1965. As with other vulgarities, these uses of the word may have been common in oral speech for some time before their first print appearances. By the 1970s, Hustler magazine featured people they did not like as "Asshole of the Month." In 1972, Jonathan Richman's Modern Lovers recorded his song "Pablo Picasso," which includes the line "Pablo Picasso was never called an asshole."