Plural of dimness; instances or qualities of being dark, not bright, or not clear.
From Middle English 'dim' (of uncertain origin, possibly from Old English 'dimm') plus Old English suffix '-ness' (state or quality) plus plural '-es'. The word evolved to describe the state of reduced light or clarity.
Dimness is one of those perfect words that sounds like what it means—the double 'm' almost makes your mouth feel the heavy darkness it describes, which is why many light-related words in English have these softer, slower sounds.
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