[keymasta]

As per my knowledge, and as per Britannica, a chord actually uses three or more notes. A two note structure is called a diad, which implies a bit of confusion in the term "power chord" (written as 5, as in G5, which == G D == 1 5).. as it is not by definition a chord but a diad.

This may be a pedantic clarification, but that is the definition

[kaoD]

TBH "definition" depends on the theory from which you're looking at the notes.

In the eyes of the Common Practice two simultaneous notes are not chords; in rock they most definitely are; in EDM you don't even care, since timbre is all that matters; in jazz you'd say "it depends" (e.g. might even be a triad with an omitted 5th... depending on context!)

Music theory is too post-hoc.