CJK Unified Ideograph-8815

It means “to wriggle or crawl slowly.” You almost never meet 蠕 alone. In Chinese it supplies the movement image inside a compound: 蠕动 can describe crawling motion or the wave-like squeezing of the digestive tract, and 蠕虫 points to a worm-like creature.

Its written history is older than this exact form. The variant dictionary says 《說文》 records 蝡, “to move,” while 蠕 is not recorded there and became the later standard form. Think motion associated with crawling creatures, not the name of one species.

What does 蠕蠕 mean?

It is a historical name, not simply 蠕 repeated.

The Northern Wei record says the group called itself 柔然, then describes the court renaming it 蠕蠕 because it judged the people ignorant and insect-like. Other dynastic histories wrote the same Rouran name as 芮芮 and 茹茹, so one group can appear under several Chinese spellings.

When a history passage gives you 蠕蠕, check the referent before glossing it as “wriggling.” The doubled spelling changes the meaning and carries that political edge.

Why does 蠕 have two readings?

The reading depends on language and lexical tradition. Mandarin dictionaries give rú for the ordinary character and also record ruǎn as an alternate reading — pinyin is the roman-letter spelling you type for Mandarin sounds. Japanese references list readings including ゼン and ジュ, with うごく and うごめく as native glosses. Copy the reading attached to your word, not one from another language.

So 蠕动 is rú dòng in Mandarin but ぜんどう in Japanese. That split is why a pronunciation lookup can look inconsistent even when the glyph is identical.