擾

A phono-semantic compound consisting of:

手 (hand) — semantic component, indicating action or intervention;

憂 (worry; yōu) — phonetic component, providing the sound. The structure suggests actions that create trouble or agitation, leading to meanings like “to disturb” or “to disrupt.”
Semantic development: - action by hand; - causing agitation or unease; - disturbing order; - interference (including technical usage). Thus, 擾 evolved from physical disturbance to social and abstract disruption.

요란 (擾亂) — disturbance; disorder

소요 (騷擾) — unrest; disturbance

Widely used in modern Chinese in both polite expressions (打扰) and technical terminology (干扰).

The shift into technical fields (e.g., signal interference) shows how traditional characters adapt to modern scientific language.

Compared to 亂, which denotes general chaos, 擾 often implies an external cause disrupting stability.
Related characters: 亂 — chaos; disorder

騷 — disturbance; agitation

干 — interference

Among these, 擾 emphasizes active disturbance caused by intervention, whether physical, social, or technical.