The ‘decimal’ is implicit to the metric system. A very handy system that seldom poses problems unless you’re trying to translate exquisite American dishes like the quarterpounder with cheese.
I would say that the decimal has its name from its primary use in a base ten numbering system - this is not bound to the metric system. We could have ended up with a base two system (where a half would be written 0.1) - or maybe better a base twelve system (so 10 would be divisible by 2 and 3, 10/2 = 6, 10/3=4, 1/10=0.1), the metric system would then have its prefixes being powers of that chosen base instead of ten. Apologies for the digression.