On a desert road paralleling a mountain range you suddenly spot a bright round object with a smooth convex top looming overhead. You’re having a close encounter with a lenticular cloud, a lens- or lentil-shaped cloud with sharp, sometimes iridescent outlines, which can be formed by strong winds blowing perpendicular to a mountain range. Lenticular means ‘lens-shaped’ or ‘pertaining to a lens or lenses.’ < late Latin lenticulāris, < lenticula, diminutive of lent-, lens ‘lentil.’
Lenses were used for magnification in ancient times. According to Pliny the Elder, Nero used an emerald as a lens to watch gladiators fight. But the knowledge of lenses seems to have been lost and it wasn’t until the 13th century that eyeglass came into use. Lens means ‘lentil’ in Latin; the glass magnifying objects were named for their resemblance to the legume.
Remember: lentils are the beans and lintels are the beams. Unless you’re from Texas. Then they’re both “lintels.”