Usage notes: What’s the difference between nightfall, dusk, and twilight? Poetry. The French word for dusk is crépuscule, which to me sounds rather ominous. I suppose the French expression entre chien et loup is too, since it suggests that the limited light prevents you from knowing whether you’re looking at a dog or a wolf,* but somehow the poetry of the expression makes it all okay.
Je n’aime pas sortir entre chien et loup.
I don’t like going out at dusk.
Nous l’avons rencontré à la plage, entre chien et loup.
We met him on the beach at twilight.
à la brunante (Canadian French)
à la brune (literary)
à la nuit tombante
à la tombée de la nuit
à l’heure bleue
Some sources, including Littré, state that entre chien et loup is also synonymous with à la tombée du jour (dawn), but Le Petit Robert and TLFi disagree.
*In the most basic sense, the dog represents the day while the wolf symbolizes the night, but you can take it much further than that.