richyoudaoicibaDictYouDict[rich 词源字典]
rich: [OE] The original meaning of rich was ‘mighty, noble’. It goes back ultimately to the Indo-European base *reg- ‘move in a straight line’, hence ‘direct’, hence ‘rule’, source of English right, Latin rēx ‘king’ (ancestor of English regal, royal, etc), and Latin regere ‘rule’ (ancestor of English regent, regiment, etc).

The Old Celtic equivalent of Latin rēx was rīx ‘king’. This was borrowed into prehistoric Germanic, where it subsequently evolved into German reich, Dutch rijk, Swedish rik, Danish rig, and English rich. (It was also taken over by the Romance languages, giving French riche, Italian ricco, etc.) The sense ‘mighty, noble’ survived in English into the late Middle Ages, but ‘wealthy’ had started to develop in Germanic, and eventually saw off ‘mighty’.
=> regal, right, royal[rich etymology, rich origin, 英语词源]
rich (adj.)youdaoicibaDictYouDict
Old English rice "strong, powerful; great, mighty; of high rank," in later Old English "wealthy," from Proto-Germanic *rikijaz (cognates: Old Norse rikr, Swedish rik, Danish rig, Old Frisian rike "wealthy, mighty," Dutch rijk, Old High German rihhi "ruler, powerful, rich," German reich "rich," Gothic reiks "ruler, powerful, rich"), borrowed from a Celtic source akin to Gaulish *rix, Old Irish ri (genitive rig) "king," from PIE root *reg- "move in a straight line," hence, "direct, rule" (see rex).

The form of the word was influenced in Middle English by Old French riche "wealthy, magnificent, sumptuous," which is, with Spanish rico, Italian ricco, from Frankish *riki "powerful," or some other cognate Germanic source.

Old English also had a noun, rice "rule, reign, power, might; authority; empire." The evolution of the word reflects a connection between wealth and power in the ancient world. Of food and colors, from early 14c.; of sounds, from 1590s. Sense of "entertaining, amusing" is recorded from 1760. The noun meaning "the wealthy" was in Old English.