The word 淤滞 is formed by combining the character 淤, which itself is a phono-semantic compound with the water radical (氵) indicating its relation to fluid and the component 於 suggesting its pronunciation, conveying meanings like silt or clogging, with the character 滞, also a phono-semantic compound using the water radical (氵) for semantic association with flow and 帶 for phonetic cues, meaning sluggish or obstructed. Together, these characters create a compound word where both elements contribute to the overall meaning of stagnation or blockage, specifically in contexts involving fluids or circulation.