simultaneousness

The narrator threw all his powers of description into the simultaneousness of Sally's arrival at this point and the gentleman walking straight over the pier-edge.

From Somehow Good by William Frend De Morgan

He analyzes the melody and, planning the arpeggiating with scrupulous fidelity, he shows why the arpeggiating "must be affected with the utmost rapidity, bordering upon simultaneousness of harmony in the case of many chords."

From Chopin : the Man and His Music by James Huneker

And to the whole bright spectacle was added the impressiveness of unfaltering rhythm and simultaneousness of movement.

From Mushroom Town by Oliver Onions

The unsuspicious parents, it seems, did not notice that the neighbors were dropping in with a very unusual simultaneousness and that after supper an unwonted fire was being built in the parlor.

From The American Country Girl by Martha Foote Crow

I think you are too well pleased with the simultaneousness.

From The Kempton-Wace Letters by Jack London