colorless

From color +‎ -less.

colorless (comparative more colorless, superlative most colorless)

1. US standard spelling of colourless.
   • 1867, Ivan Sergheïevitch Turgenef [i.e., Ivan Turgenev], chapter I, in Eugene Schuyler, transl., Fathers and Sons […], New York, N.Y.: Leypoldt and Holt, →OCLC, page 1:

     The servant to whom he put this question was a young fellow with chubby cheeks, small, dull eyes, and a round chin, covered with a colorless down.