You know the concept of "cross" existes independently of Roman upright torture perpendicular crosses?
A crossroad is not upright, a cross-section is not always perpendicular. All x and + and × are crosses, two bars crossed.
The concept is crossing, aka. meeting. The way it's positionned is irrelevant.
That's exactly what I'm saying. It's nonsensical to say that "well X means the letter, even though that came later." Just as it would be nonsensical to say that an upright cross is religious iconography.
X has been used for all kinds of things, such as, ya know, a marker. X marks the spot, meaning it's the primary place where your attention should go. X is used to cross out things. Multiple Xs have various meanings. Many of these existed long before the letter X existed.
Yes, it is under the subsection of cross, but so are trucks under the subject of cars, and yet we say cars vs trucks all the time in common parlance, so as to distinguish them -- this is a useful distinction because a car does not have a bed, and a truck does. Given X has a generic meaning, including outside of letters, and the other kind of cross, the upright cross doesn't really have a name (just as sedans, coupes, and minivans don't really have a collective name to distinguish them from trucks with beds), it makes sense to call the latter cross, and the former X. "Plus sign" is a bit unwieldy, and specifically refers to math so ehh.
Words have many meanings, and the tweet is silly by acting like everyone can only refer to one specific meaning of the symbol, that of a letter. X is not just a letter. It's the word we have for a diagonal cross. It's weird and awkward to call it a cross, since most people (as evidenced by the poll above) associate a cross with the upright variety.
Matematically, a square is a diamond though. You can't draw a square that doesn't have diamond's propieties.
Right. That..doesn't change what I'm saying at all. I specifically brought them up because they have the exact same properties, but are viewed at a different orientation.
We don't use "diamond" so much in math, but it is still a colloquial shape. It's useful in common speech.