严肃 (serious / solemn) is the most common compound.
Components
ideograph
肃sù
respectful; solemn
Modern simplified form rebuilt from the complex traditional 肅, which originally depicted a hand holding a writing brush (聿) over a deep pool - a scribe in concentrated reverence. The simplification telescoped the lower portion into stylised crossing strokes. Indexed under Kangxi #129 聿 by tradition, though no visible 聿 survives.
Filed under radical 聿 (yù, #129) by convention. 聿 is not a separate component in 肃, so no strokes are highlighted.
