Why do we use the terms AC and DC if they have nothing to do with current?
It's not true that you usually talk about voltage, in transistor application current is usually way more important. In fact galvanometers actually measure current (magnetic field is generated by current), and that was until some years ago the preferred way to measure voltage, too.
The trick is that they are related by resistance (Ohm said so) and since usually resistance is constant (at least for the loads of the time) a continuous current produces a continuous voltage.
If you really want to go linguistic, the real issue is saying &quot;DC voltage&quot; or &quot;DC current&quot;: the first has not really sense (direct current voltage? meh), the second one is like saying &quot;LED diode&quot; (current is already in acronym)
By the way, languages vary: in italian we use &quot;corrente continua&quot;, &quot;corrente alternata&quot;, &quot;tensione continua&quot;, &quot;tensione alternata&quot;: no redundant acronyms and &quot;direct&quot; is replaced by &quot;continuous&quot; which is arguably a better choice.
PS: and don't forget about the &quot;conventional direction of flow&quot; thing!