Ley, also lay, lei, lai, laige or lägge, and, accourding to Grimm, leie, is a commonly occurring name for rocks or crags in the Rhenish and Lower German language regions. It is derived from the Old Saxon word, lêia. It is particularly associated with rock precipices (Felsabbrüche) and rock faces (Felswände), but also with rock slabs (Felsplatte). In addition, it is also used in the sense of shale or slate (Leienstein), and also to mean "slate" in the sense of a blackboard or roofing tile (Leiendecker). Its Dutch form is leyde or leye.
- Loreley, a well known slate hill on the Rhine
- Tholey, parish and abbey in the northern Saarland
- Theley, a village in the parish of Tholey
- Erpeler Ley, a basalt rock face above the Rhine
- the Koblenz quarter of Lay
- Kaiserlei, a quarter in the city of Offenbach, named after a rock above the River Main
- the Rabenlay is a hill in the Siebengebirge range, at the foot of which was found the double grave of Oberkassel.
- the Rabenlay is a shallows in the Rhine at river kilometre 548.5-549.0 near Oberwesel
- Mendiger Ley, basalt mine
- Leybucht near Norden (East Frisia)
- Plästerlegge ("raining slate rock"), waterfall near the Bestwig village of Wasserfall
- Geierlay in (Mörsdorf Hunsrück), Germany's second longest suspension bridge
- Friedrich Woeste: Wörterbuch der westfälischen Mundart. Leipzig, 1882, p. 155 (online)
- Reinhard Pilkmann-Pohl: Plattdeutsches Wörterbuch des kurkölnischen Sauerlandes. Strobel-Verlag, Arnsberg 1988.
- Eintrag LEIE,LEI, f. fels, stein. In: Jacob Grimm, Wilhelm Grimm: Deutsches Wörterbuch. Leipzig 1854-1960 (dwb.uni-trier.de)
- Forum Keltic Studies zu Lei
- "Vulkanschule: Die Museumslay" (in German). Vulkanpark, Nationaler Geopark Vulkanland Eifel. Retrieved 2015-05-26.