镝

Chemistry uses 镝 for dysprosium; older weapon texts use it for arrowheads. In Mandarin pinyin, dī has a high, level first tone; dí has a rising second tone. The surrounding compound tells you which reading fits.

Older Chinese compounds use 镝 in literary references to weapons and whistling signal arrows. The Japanese term 鏑矢 (kaburaya) names a historical or ritual whistling arrow, recorded by the Kamakura period. Traditional Chinese and Japanese use 鏑; simplified Chinese writes 镝.