Adverb
to an inexpressible degree
Source: WordNetHeaven's ebon vault Studded with stars unutterably bright, Through which the moon's unclouded grandeur rolls, Seems like a canopy which love has spread To curtain her sleeping world. Percy Bysshe Shelley
When I was a child people simply looked about them and were moderately happy; today they peer beyond the seven seas, bury themselves waist deep in tidings, and by and large what they see and hear makes them unutterably sad. E. B. White
Why is it so unutterably beneficial, the thought that someone besides myself knows me? Karen Horney
Vain are the thousand creeds That move men's hearts: unutterably vain. Emily Brontë
The human heart is a great city, teeming with myriad people, full of business and mighty doings, and we wander its crowded streets unutterably alone; we do not know what it is all about. Frank Crane
Just as the blessings of God are unutterably great, so their acquisition requires much hardship and toil undertaken with hope and faith. Macarius of Egypt