辣
ラツ, から.い

pungent, spicy, harsh, cruel, severe

JLPT0 G7 S14 F5000

束 here an abbreviated form# of 剌 (sharp) + 辛 needle/cutting tool → *severe* pain caused by a sharp weapon → *violent* (activity/pain). Also, *hot*, *spicy* and *bitter* (← sharp taste).

[Full Kanji Etymology List]