ワイシャツ

Etymology
, borrowed from, from the typical white color of dress shirts.

The meaning in Japanese evolved over time to extend first to any dress shirt, regardless of color, and then to any long-sleeved button-down shirt in general.

First cited to 1912. uses the term in his 1915 book with the spelling, using furigana to indicate a pronunciation of.

Noun

 * 1)  a dress shirt
 * 2)  a long-sleeved button-down shirt