Wiktionary
undecorative
a. 1 not decorative 2 unsightly, displeasing to the eye
Usage examples of "undecorative".
They will leave the caravans and undecorative wagons until last, and follow us when they are ready.
Like the door facing the desk, through which Lando had been escorted, both were framed in plain undecorative alumabronze, the spare motif echoed in wainscotting, baseboards, and a border around the high, somehow intimidating ceiling.
Just a plain black phone, as utilitarian and undecorative as the desk itself.