late 14c., from Old French eloquence (12c.), from Latin eloquentia, from eloquentem (nominative eloquens) "eloquent," present participle of eloqui "speak out," from ex "out" (see ex-) + loqui "to speak" (from PIE root *tolkw- "to speak"). Earlier in same sense was eloquency (mid-14c.).
Eloquence is a word which has been made the expression for the highest power of speech in producing the effect desired, especially if the desire be to move the feelings or the will. Many efforts have been made to define eloquence, some regarding it as a gift and some as an art. "It is a gift of the soul, which makes us masters of the minds and hearts of others." (La Bruyère.) [Century Dictionary]