Noun : "Man," "eye," "strength," and "sixths" are English words of one syllable. ,Do not breathe a syllable of all this.    From Dictionary.com. 

Then ensued a wild and terrible commingling of unsyllabled sounds, so unearthly that it is not in the power of language to fitly describe them.    From Wordnik.com.  [Hygienic Physiology : with Special Reference to the Use of Alcoholic Drinks and Narcotics] Reference

Fit names are not given, but grow; and we believe there is not a spot in the land, possessing any attractiveness, but has its name ready fitted to it, waiting unsyllabled in the air above it for the right sponsor to speak it into life.    From Wordnik.com.  [The Atlantic Monthly, Volume 05, No. 30, April, 1860] Reference

Jerry swung from the adjacent oak, turning here and there the unseeing orbs in unsyllabled prayer for the common.    From Wordnik.com.  [A Fool's Errand. By One of the Fools] Reference

Bel was hardly equal yet to five-minute Crambo; and besides, she was doing her best; trying to put something clearly into syllables that said itself, unsyllabled, to her.    From Wordnik.com.  [The Other Girls] Reference

The voice sunk into a faint whisper whose sounds were unsyllabled -- an occasional murmur escaped them once after, in which the name of his niece was again heard; exhibiting, at the last, the affection, however latent, which he entertained in reality for the orphan trust of his brother.    From Wordnik.com.  [Guy Rivers: A Tale of Georgia] Reference

And the mountains smiled not, neither wept, but gravely and kindly folded over, about, behind, the gray mantle of the cañon walls, and locked fast doors of adamant against all following, and swept a pitying hand of shadow, and breathed that wondrous unsyllabled voice of comfort which any mountain-goer knows.    From Wordnik.com.  [The Singing Mouse Stories] Reference

Some heretics there are in the city, who say thy merit is but a trick of song shared by thee in common with the birds, .. who truly seem to take no pride in the particular sweetness of their unsyllabled language, .. but thou thyself art better instructed, and who shall blame thee for the veneration with which thou dost daily contemplate thine own intellectual powers?.    From Wordnik.com.  [Ardath] Reference

Names not less dear, unsyllabled by fame.    From Wordnik.com.  [The Poetical Works of Oliver Wendell Holmes — Volume 09: the Iron Gate and Other Poems] Reference