The answer is actually very simple. The “T” in “T-shirt” refers to the shape of the shirt.
When a T-shirt is laid flat, the body of the shirt forms a straight vertical line, while the sleeves stretch out to both sides. Together, they create the shape of a capital letter “T.” That is where the name comes from.
It is not short for a secret word. It does not stand
for “training,” “textile,” or “top.” It simply describes the appearance of the shirt when viewed flat.
