Limn? Damn! How are we to say this word? And why does it have that form? It looks all folded up, like a stack of sheets turned on its side, or perhaps a shelf of library books. Can we illuminate this a bit? Has it been milled down to some minimal form from some larger animal, or has it grown an extra limb? Are we seeing a word in a liminal form, or is this lexical sediment?
To start with: You don’t say the n. It’s just there for looks. This word is pronounced the same as limb, which may well be one reason it’s not used much anymore.
Is it related to limen and liminal, those words relating to thresholds (threshold, by the way, is a word that compensates for silent letters by having a sound that is not written in – the phantom second h, eliminated or illuminated in the limen)? No, it is not, even though it has so many sounds in common. And eliminate? That’s another threshold word – the e means ‘out’ or ‘from’; thus, ‘toss over the threshold’.
Is it related to limb? No, and they come to their parsley consonants from opposite directions (meeting on the threshold, perhaps?). The word limb meaning ‘arm, leg, tree branch’ comes from an old Germanic word lim. It just happened that there was also a Latin word limbus meaning ‘rim’ that wore down to limb meaning ‘edge of a disc (e.g., moon, sun, planet)’ or ‘expanded part of a leaf, petal, or sepal’ (as per Collins). Most likely this second limb led to the addition of the b to lim, because we are drawn to unphonetic orthography as moths are drawn to light.
Which is not to say that these odd spellings illuminate! No, but the n and b are in their way like illuminations: ornamental illustrations added to manuscripts, as for instance ornate capital letters. One might even call them visual hymns. It just happens that they don’t cast much light. But in the case of limn there is a dimn – sorry, dim – glow. When you lit up a manuscript with these illuminations, you could be said (in former usage) to lumine it. You make it luminous! But as candles burn down, so too do pronunciations wear down, and the spelling is trimned. I mean trimmed. So lumine became limn. And it carried the illustrative sense, coming to mean ‘depict, paint a picture, portray’.
Given the sound, one may imagine that it has to do with drawing lines or with laminating. But those words, too, are unrelated. It is simply a word for ‘light’ that has been lightened.
Its semantic emanations are dimned; it is now mainly a word used vaguely by pretentious scribblers to mean ‘drawn, painted, depicted’. It may be a light word, but it carries the weightiness of that excrescent consonant, so those who fancy their own scribery are drawn as a moth to the inevitable luminescent silent n.
Thanks to Ron Callahan for suggesting this word.