Origins
The English word 'south' descends from Old English 'sūþ,' from Proto-Germanic *sunþrą, and its etymology connects it directly to the sun. The prevailing scholarly view links *sunþrą to the PIE root *suh₂n- (sun), making 'south' literally 'the sun-side' or 'the sun-direction.' For peoples living in the Northern Hemisphere, this is observationally precise: the sun's daily arc across the sky passes through the southern portion, and at noon it stands due south.
This solar etymology is widely accepted but not without complications. Some linguists have proposed alternative derivations, but the phonological fit between *sunþrą and *suh₂n- is strong, and the semantic logic is compelling. The same PIE sun-root produced Latin 'sōl,' Greek 'hēlios' (through a different ablaut grade), Old English 'sunne,' and Gothic 'sunnō.' If the connection holds, then 'south' and 'sun' are ultimately the same word, diverged through different suffixation.
The Germanic cognates are consistent: German 'Süd,' Dutch 'zuid,' Old Norse 'suðr,' Old Frisian 'sūth,' and Gothic 'sunþs' (from the south). Like 'north,' the word was borrowed into Romance languages from Germanic — French 'sud,' Italian 'sud,' Spanish 'sur' — replacing the Latin term 'merīdiēs' (midday, i.e., the direction of the noonday sun) in common usage, though 'meridional' survives as an adjective meaning 'southern' in several Romance languages.
Old English Period
The phonological development from Old English 'sūþ' to Modern English 'south' involves the Great Vowel Shift, which diphthongized the long /uː/ into /aʊ/. The same shift affected 'house' (OE 'hūs'), 'mouse' (OE 'mūs'), and 'out' (OE 'ūt'). The final consonant, a voiceless dental fricative /θ/, has remained unchanged.
Place-names throughout the English-speaking world preserve the word. Sussex is 'south Saxons' (as opposed to Essex, 'east Saxons,' and Wessex, 'west Saxons'). Suffolk is 'south folk' (versus Norfolk, 'north folk'). Southampton, Southwark, and South Carolina all carry the directional marker. Perhaps the most etymologically ironic place-name is Sutherland, a region in the far north of Scotland. The Norse settlers who named it were based in Orkney and Caithness, still farther north; to them, the Scottish mainland to their south was indeed 'suðr land,' their southern territory.
The compound 'southern' descends from Old English 'sūþerne,' using the same adjectival suffix seen in 'northern,' 'eastern,' and 'western.' The word 'southward' (OE 'sūþweard') uses the directional suffix '-ward.' The specialized navigational term 'sou'wester' — both a wind direction and a type of waterproof hat — shows how thoroughly directional vocabulary penetrated the maritime language of English seafarers.
Latin Roots
Culturally, 'south' has accumulated powerful metaphorical meanings beyond mere direction. In many Northern Hemisphere cultures, south connotes warmth, fertility, and ease — reflected in phrases like 'heading south for the winter.' In Chinese cosmology, south is associated with fire, summer, and the color red; the Chinese emperor traditionally faced south when holding court, making south the direction of authority. In medieval European maps, south was sometimes placed at the top (these are called 'T-O maps'), and the word 'orientation' itself — from Latin 'oriens' (east, rising) — reveals that east, not north, was originally the default direction of map alignment.
The metaphorical use of 'going south' to mean 'deteriorating' or 'declining' is relatively modern, first attested in American English around the mid-twentieth century, possibly influenced by stock-market charts where downward movement on a north-oriented graph moves visually toward the south.