to damage or spoil the appearance or quality of something.
From 'be-' plus 'mar' (to damage or spoil). The combination creates a verb suggesting to thoroughly damage or ruin something.
This word shows the blurry line between obsolete words and ones still living—'mar' is still common, but 'bemar' never caught on, perhaps because it didn't add enough meaning beyond its base word.
Complete word intelligence in one call. Free tier — 50 lookups/day.