The quality or state of being dismal; gloominess, dreariness, or bleakness.
From dismal + -ity (Latin suffix forming abstract nouns). This formation is typical of Early Modern English but has become rare as 'dismalness' is now preferred.
Words ending in -ity like 'dismality' feel formal and old-fashioned compared to -ness words, which is why you'll find 'dismality' in Victorian novels but 'dismalness' in modern writing.
Complete word intelligence in one call. Free tier — 50 lookups/day.