The phrase "eloquent language" is correct and usable in written English.
You can use it to describe someone who speaks or writes in an impressive, articulate way. For example, "John's eloquent language and well-reasoned arguments were instrumental in convincing the board to approve the project."
She has developed a subliminal but eloquent language through clothing and accessories.
This family venerates a certain idea of France -- literature, eloquent language, Enlightenment principles.
By the end, Homans writes, MacMillan "had reduced ballet's eloquent language to a series of barely audible grunts".
In their place, he has developed a most eloquent language of full-body communication (but one that makes, say, back problems all the more troubling).
"My heart became attached to them," he said of the Taliban, as if translating from a finer, more eloquent language than the one to which he was born.
Nor was "Humanae Vitae" simply an argument for openness to having children in marriage, although the encyclical certainly includes eloquent language about that.
In reaction, at a White House dinner dramatically lighted with candles, Bartlet delivers an eloquent speech that resonates with the language of real events and fears.
The real story is played out between the lines, in fumbling pauses and eloquent body language.
In eloquent, plaintive language, he told his closest family that he was miserable and that the war was a mistake.
Her spare but eloquent quilt language involved a mastery of appliqué techniques, tribal emblems, Masonic devices and biblical imagery.
Paine's eloquent, direct language spoke people's unspoken thoughts; no pamphlet had ever made such an impact on colonial opinion.
