If it’s not “commercial” or “commerce” what might it be?
communist
compact
commander
complete
communicable
complex
I always assumed it stood for “Computer” but I’m sure that’s not right.
It’s “commercial.”
ETA: Though not all .com sites are commercial now. But that was the original derivation.
Back on the old days, among domains available to anyone, there were “.com” for commercial organizations, “.net” for network providers, and “.org” for non-commercial organizations. Somehow the distinction between them was lost early on, and commercial organizations were able to register names in the .net and .org domains, and vice versa. I wonder whether this started because some commercial organizations were also network providers?
(The other three-letter top-level domains were restricted: .mil for US military, .edu for US educational, .gov for US government, .int for international organizations. The two-letter country-specific top-level domains like .ca for Canada were a completely-separate set.)