The point is not that "backslash" sounds unrefined. "Backslash" is fine when you're referring to a backslash (reverse solidus). What's not fine is saying back

The point is not that "backslash" sounds unrefined. "Backslash" is fine when you're referring to a backslash (reverse solidus). What's not fine is saying backslash when you are in fact referring to a plain ol' slash (solidus), as in URLs. People who refer to domain "extensions" share something in common with people who misapply the term "backslash". Nerdy enough to have heard of (file name) "extensions" and "backslashes", not nerdy enough to care whether the term is actually appropriate for what they're trying to refer to in the present. TLDs are not "extensions". The occasional domain registrar that refers to them this way in marketing copy make me wince the hardest. They don't have the excuse of co-opting technically incorrect but extremely popular misnomers. It's more like, if anything, they're most likely to be the cause of people using the wrong term, if ever it were to become a trend.