sameness

samanlaisuus the quality of being the same; identity
1922, (w), w:Babbitt (novel)|Babbitt, New York: Harcourt, Brace & Co., Chapter XXXIV, p. 391, https://archive.org/details/babbittl00lewi

All of them agreed that the working-classes must be kept in their place; and all of them perceived that American Democracy did not imply any equality of wealth, but did demand a wholesome sameness of thought, dress, painting, morals, and vocabulary.

However strange it may sound, it always seemed to me (..) that Adrian's laughter-filled friendship with Schildknapp had something to do with the sameness of their eye color

O to sail to sea in a ship! / To leave this steady unendurable land, / To leave the tiresome sameness of the streets, the sidewalks and the houses, / To leave you, O you solid motionless land, and enter a ship, / To sail and sail and sail!

(..) in the time when day follows day in dull, unexpectant sameness, and trial is a dreary routine,—it is then that despair threatens (..)