The quality of being bland, dull, and lacking distinctive or memorable features; the state of being forgettable or generic.
From characterless plus -ness (suffix forming abstract nouns). Built on character (from Greek charaktēr) plus -less plus -ness, creating a three-part word expressing total absence of distinction.
When something has 'characterlessness,' it means it's so forgettable and generic that you can't even remember what it looked like five minutes later—it left zero marks or impressions on your memory.
Complete word intelligence in one call. Free tier — 50 lookups/day.