Origins
The English adjective 'wide' is a fundamental spatial term whose etymology reveals an unexpected conceptual origin: not breadth itself, but the act of separation that creates breadth. It comes from Old English 'wīd,' meaning 'broad,' 'spacious,' 'extensive,' and 'far-reaching,' from Proto-Germanic *wīdaz, from the PIE root *h₁weydʰ- meaning 'to separate' or 'to divide.' Width, in the deepest etymological sense, is the space that opens up when things are pulled apart.
This connection to separation links 'wide' to some surprising relatives. Latin 'viduus' (bereft, deprived, widowed) derives from the same PIE root, giving English 'widow' through a different line of descent (via Old English 'widuwe,' from Proto-Germanic *widuwō). The semantic thread connecting 'wide' and 'widow' is separation: a wide space is one where the sides have been divided; a widow is one who has been divided from a spouse. Latin 'dividere' (to divide) may also be connected, though some scholars derive it from a different but phonologically similar root.
The Proto-Germanic cognates are consistent and transparent. German 'weit' means 'wide,' 'far,' and 'extensive,' and is one of the most common adjectives in the language. Dutch 'wijd' means 'wide' or 'spacious.' Old Norse 'víðr' meant 'wide' and appears prominently in the name 'Víðarr' (a Norse god associated with vast, silent spaces) and in the poetic epithet for the world, 'víðr heimr' (the wide world). Gothic 'wids' is attested with the meaning 'wide.'
Old English Period
In Old English, 'wīd' was both an adjective and an adverb. The adverbial use — 'wīde' meaning 'widely' or 'far' — was extremely common, appearing in formulas like 'wīde geond eorðan' (widely throughout the earth). The compound 'wīdsǣ' (wide sea) was a poetic synonym for the ocean. The word 'width' is a relatively late formation: Old English had 'wīdnes' (wideness), but 'width' (modeled on 'breadth' from 'broad') did not appear until the seventeenth century.
The semantic range of 'wide' in Modern English extends well beyond physical space. 'Wide' can describe knowledge (wide reading), influence (wide impact), applicability (wide-ranging), difference (a wide gap between opinions), and accuracy (wide of the mark, meaning inaccurate — originally an archery term where the arrow lands far from the target). In cricket, a 'wide' is a ball delivered too far from the batsman, a use dating from the sport's early codification.
'Wide-eyed' has two distinct senses: literal (with eyes opened wide, suggesting surprise or innocence) and figurative (naive, credulous). 'Wide awake' (fully alert) dates from the eighteenth century and was used as the name of a broad-brimmed hat in the nineteenth century, as well as for a political movement — the Wide Awakes — supporting Abraham Lincoln in 1860. 'Widespread' (extending over a large area) is attested from the seventeenth century.
Later Development
The World Wide Web, coined by Tim Berners-Lee in 1989, uses 'wide' in its fullest sense of global extent. The abbreviation 'www' has made the word 'wide' part of the most frequently typed string in computing history, giving an Old English spatial adjective an entirely unforeseen digital afterlife.
The relationship between 'wide' and 'broad' in English is a case of near-synonymy with subtle differentiation. Both mean 'of great extent from side to side,' but 'wide' tends to emphasize the distance between two edges (the opening, the gap, the span), while 'broad' emphasizes the surface or area itself. A river is 'wide' when we focus on the difficulty of crossing it; a man's shoulders are 'broad' when we focus on their impressive expanse. This distinction is not rigid, but it reflects the words' different etymological orientations: 'wide' from separation, 'broad' from spreading.
In Old English poetry, 'wīd' was a word of grandeur and scope. The 'wīde worold' (wide world) was the whole of creation; the 'wīde sǣ' (wide sea) was the terrifying, magnificent ocean that separated lands and peoples. The word carried a sense of awe before immensity that still echoes, faintly, when we speak of 'the wide open spaces' or gaze at a 'wide' horizon.