Switch – Is a “LAN” a layer 2 or a layer 3 concept, in TCP/IP

I think my question is purely theoretical and a matter of definitions; it derives from the fact that a L2-switch with VLAN capabilities is able to "create" different virtual LANs, and thus I am led to believe that "LAN" is a L2 concept. However, I've only recently thought about that, and I've always been used to the concept of LAN as a layer 3 thing, especially after university exercises. For example, if I have a network with a host, connected to a L2-switch, with the latter connecting another host and a router, then in an equivalent logical representation for identifying LANs, I would say that whatever is on one port of the router is a LAN, and whatever is on the other side is another LAN, thus replacing the switch with a "logical link". This makes me think, instead, that a router is what's needed to distinguish between a LAN and another – I can have multiple layer 2 switches and still be on the same LAN, provided that they don't use any VLAN capability. But then again, a router has both L3 and L2 capabilities, so this doesn't imply that a LAN isn't a L2 concept. I then thought, in order for 2 different LANs (or VLANs) to communicate, a router is needed, thus one may infer that when there's a router, it can be used to connect different LANs, hence we see it as a "LAN separator" in a logical scheme. But if that's true, then I can't understand what actually discriminates between a LAN and another, which factors do by definition. I may be confusing stuff, but I really can't find a precise definition for "LAN" as I only find very broad ones.