Yes, these names can mean something, but not always the same kind of thing.

For Leica/Leitz, the traditional names mainly indicate maximum aperture rather than a specific optical formula. Examples from the community answers:

• Noctilux: at least f/1.2
• Summilux: f/1.4
• Summicron: f/2
• Summarit: currently f/2.5
• Elmarit: f/2.8
• Elmar: about f/3.5 to f/4 Also, a Vario- prefix generally means a zoom lens.

For Carl Zeiss, names such as Planar, Tessar, Sonnar, Distagon, and Biogon refer more to optical design families. In practice, that means they originated as different lens formulas or design approaches.

From a buyer’s perspective: they are useful as clues, but not enough on their own to judge a lens. A Leica name may quickly tell you how fast the lens is, while a Zeiss name may hint at its design heritage. But actual image quality, focal length, size, autofocus/manual focus, and compatibility still matter more than the family name alone.