Dark is ambiguous: it can mean light is not emitted, but it can also mean light is absorbed.

Even going with the first one, it's an incomplete description at best. "Dark" matter does not simply fail to emit light; it does not interact with light at all (other than by gravity, and that only bends it slightly, no absorption or emission involved).

Transparent fully captures this.

The overloaded meanings of those words which you are invoking are not relevant to the description of a physical property.

> "Dark" matter does not simply fail to emit light; it does not interact with light at all

We don’t know this. We have a parcel of observations from which we are trying to intuit a cause.

Those are two separate things:

1) We have unexplained observations.

2) A hypothetical explanation is dark matter, defined as a form of matter which does not interact with light (other than through gravity).

Whether dark matter actually exists does not affect how it's defined.