inexplainable

He made no reply and continued to stare at them as if he thought it inexplainable that two white men should suddenly invade his sleeping quarters.

From The Mark of the Knife by Clayton H. Ernst

On an afternoon three weeks after Beryl's sudden and inexplainable departure, the drowsy quiet of the old Manor was broken by a shrill voice lifted in frenzied protest against Harkness' deeper tones.

From Red-Robin by Harriet Roosevelt Richards

In gathering such information as human responses, I began to realize why I disliked certain people and ways of life, whereas previously, I had merely felt inexplainable disgust or anger.

From Through these Eyes The courageous struggle to find meaning in a life stressed with cancer by Lauren Ann Isaacson

The third, and to me the most remarkable, class is found not in certain personages or superstitious and determined proceedings, but in sudden and capricious scenes, and in improbable and inexplainable apparitions.

From The Philippine Islands, 1493-1898 - Volume 40 of 55 1690-1691 Explorations by Early Navigators, Descriptions of the Islands and Their Peoples, Their History and Records of the Catholic Missions, as Related in Contemporaneous Books and Manuscripts, Showing the Political, Economic, Commercial and Religious Conditions of Those Islands from Their Earliest Relations with European Nations to the Close of the Nineteenth Century by Emma Helen Blair

It was almost May, and that subtile, inexplainable joy of the springtime made it a gladness even to be alive.

From John Ward, Preacher by Margaret Wade Campbell Deland