Origins
The English adjective 'rich' traces an unexpected path through the language families of Europe, revealing ancient cultural contacts between Celtic and Germanic peoples. It descends from Old English 'rīce,' meaning 'powerful, mighty, of high rank, ruling,' from Proto-Germanic *rīkijaz, meaning 'powerful, authoritative.' But this Proto-Germanic word was not native to the Germanic family — it was borrowed at a very early date from a Celtic source, *rīgos (king, ruler), which descended from PIE *h₃reǵ- (to move in a straight line, to direct, to rule).
This Celtic-to-Germanic borrowing is one of the oldest and most significant loanwords in the Germanic languages. It must have occurred before the individual Germanic languages separated, since the word appears in all of them: German 'reich' (rich, and as a noun, 'empire' — as in 'Deutsches Reich'), Dutch 'rijk,' Swedish 'rik,' Danish 'rig,' Norwegian 'rik,' Icelandic 'ríkur,' and Gothic 'reiks' (ruler, chief). The borrowing tells us something about early Celtic-Germanic contact: the Celtic peoples, who dominated much of Europe before the Germanic expansion, apparently held a prestige that led their neighbors to adopt their word for kingship and power.
The PIE root *h₃reǵ- is one of the most politically productive roots in the family. In Latin, it produced 'rēx' (king, genitive 'rēgis'), which gave English 'regal,' 'royal' (through French), 'reign,' 'regent,' 'regicide,' 'regime,' 'region' (an area under rule), and 'regular' (according to the rule). In Sanskrit, it produced 'rājan' (king), the source of 'rajah' and 'maharaja.' In Irish, it produced 'rí' (king), preserved in names like Rory (from 'ruaidrí,' red king). The Gothic form 'reiks' was borrowed into Finnish as 'rikas' (rich), demonstrating how the word continued to move across language boundaries.
Old English Period
The semantic shift from 'powerful' to 'wealthy' is a natural metonymic development — the most visible attribute of those in power was their material abundance. This shift was already underway in Old English, where 'rīce' could mean both 'powerful' and 'splendid, magnificent,' and it was complete by the end of the Middle English period. The Old French form 'riche' (wealthy), which English also absorbed after the Norman Conquest, reinforced the financial meaning. Modern English 'rich' has largely lost the sense of political power, retaining only the sense of material wealth and abundance.
The noun 'riches' has a curious grammatical history. It derives from Old French 'richesse' (wealth), a singular noun. English speakers reinterpreted the final '-es' as a plural marker, creating the impression that 'riches' was the plural of 'rich.' This false analysis means that 'riches' takes plural agreement ('riches are') even though it was historically singular. The phenomenon is called folk etymology or morphological reanalysis.
The suffix '-ric' in words like 'bishopric' (the domain of a bishop) preserves the old sense of 'realm, domain of rule,' from Old English 'rīce' used as a noun meaning 'kingdom, realm.' This is the same word as the adjective, used substantively. German 'Reich' (empire, realm) is the direct cognate: 'Frankreich' (France, literally 'realm of the Franks'), 'Österreich' (Austria, literally 'eastern realm').
Latin Roots
The extended meanings of 'rich' in modern English — rich food (full of fat or flavor), rich colors (deep and vivid), rich soil (highly fertile), a rich voice (full and resonant) — all share the semantic core of abundance and fullness. These extensions developed primarily in Middle and Early Modern English and mirror similar developments in the Romance languages: French 'riche' can also describe food, colors, and soil.
The verb 'enrich' entered English from Old French 'enrichir' in the fourteenth century, and it has maintained both literal (to make wealthy) and metaphorical (to improve, to add value to) senses throughout its history. The noun 'enrichment' has acquired a specific technical meaning in nuclear physics — uranium enrichment — that would have been unimaginable to the medieval speakers who first used the word.
The surname Rich, and its variants Riche and Ritchie, derives from the adjective, originally given as a nickname to wealthy individuals or, ironically, to poor ones. The personal name Richard, however, has a different etymology: it comes from Proto-Germanic *rīk- (ruler) plus *harduz (brave, hardy), meaning 'brave ruler' — combining the same Celtic-borrowed element with a native Germanic one.