“Insouciance” in French refers to the quality of recklessness, although Chanel Rouge Allure Extrait de Gloss in Insouciance (#51) is a rather quiet nude tone with very subtle shimmer.
This is a lovely light color that will blank out most color on pigmented lips, leaving a sheen and a touch of natural color showing through. If you are looking something that is even more toned down than the pink-nude Confidence, then Insouciance is a good choice. Keep in mind that this collection also has a brown shade–Impertinence–if you are looking for a darker shade in the nude/brown category.
Looking at the other Chanel glosses that I happened to have in my collection, I found that Insoulance bore the closest resemblances to the more shimmery and more Chanel Aqualumiere Gloss in Freeze /Cafe Glace (#66) and Chanel’s Creme Gloss Lumiere in Creme Caramel (#76), which comes in the tube with the brush tip. I suspect that the Creme Gloss Lumiere’s have been phased out now that the Extrait de Glosses are introduced, as the supply of the former has dwindled nearly out of existence on Chanel.com’s website. Note that the Extrait de Gloss gives longer wear and a higher gloss than the Aqualumeire gloss, for those trying to decide between Freeze/Cafe Glaze and Insouciance.
One quick picture of Insouciance on bare lips: