surroundyoudaoicibaDictYouDict[surround 词源字典]
surround: [15] Although surround means ‘exist round’ something, it has no etymological connection with round. It comes via Old French suronder from late Latin superundāre ‘overflow’. This was a compound verb formed from the prefix super- ‘over’ and undāre ‘rise in waves’, a derivative of unda ‘wave’ (source of English undulate).

English took the word over in its original sense, and this survived into the 17th century (an Act of Parliament of 1609 noted that ‘the sea hath broken in … and hath decayed, surrounded, and drowned up much hard ground’). The modern sense ‘exist round, encircle’ arose in the early 17th century, presumably by association with round.
=> abundant, redundant, sound, undulate[surround etymology, surround origin, 英语词源]
surround (v.)youdaoicibaDictYouDict
early 15c., "to flood, overflow," from Anglo-French surounder, Middle French soronder "to overflow, abound; surpass, dominate," from Late Latin superundare "overflow," from Latin super "over" (see super-) + undare "to flow in waves," from unda "wave" (see water (n.1); and compare abound). Sense of "to shut in on all sides" first recorded 1610s, influenced by figurative meaning in French of "dominate," and by sound association with round, which also influenced the spelling of the English word from 17c. Related: Surrounded; surrounding.