Is it farther or further?
1580s, "flowing freely" (of water, also of speech), from Latin fluentem (nominative fluens) "lax, relaxed," figuratively "flowing, fluent," present participle of fluere "to flow, stream, run, melt," from PIE *bhleugw-, extended form of *bhleu- "to swell, well up, overflow" (cf. Latin flumen "river;" Greek phluein "to boil over, bubble up," phlein "to abound"), an extension of root *bhel- (2) "to blow, inflate, swell;" see bole. Used interchangeably with fluid in Elizabethan times. Related: Fluently.