剧

Knife radical on the right — the upright form of 刀 always cuts on the right edge of a character. It marks 剧 in the cutting-action family: 削 to whittle, 刺 to stab, 割 to cut. The knife pairs with 'fierce/intense' to give 剧's senses: severe (剧烈), and theatrical (剧场), where ancient drama meant violent stage spectacle.

Left side is 居 'to dwell', supplying the sound — jū drifting to jù with tone shift. In the traditional 劇 the left was 豦 (a fierce-tiger graph), which the simplification swapped for the more familiar 居. The drift cost the etymology some bite but gained transparency for modern learners.