How to Write 厣 (yǎn) — Meaning “operculum (shell lid)”

Picture a snail's shell (厂) with a tight lid (the inner part 弇) that seals the opening. Imagine the inner part as a "lid" that looks like a curved trapdoor protecting the snail inside. This visual helps link 厣 to its meaning "operculum."

The outer radical 厂 is written first as a horizontal stroke then a left-falling stroke, and it should be wide enough to cover the inner part. The inner part 弇 has a top 大-like shape (but with a horizontal stroke instead of a left-falling stroke) over a lower 廾-like component—make sure the lower strokes are balanced and not too close together. A common mistake is making the inner part too tall or narrow, which ruins the proportion of the enclosing 厂.

厣 (yǎn) means operculum (shell lid) and contains 弇 inside, while 厗 (tí) is a rare character meaning "hard" or "tough" and has a different inner component (usually 辛). 厘 (lí) means "centi-" or "to regulate" and has 里 inside. Visually, 厣 has a more complex inner part with a covering shape, whereas 厗 and 厘 have simpler, different inner radicals. In usage, 厣 is specific to biology (shellfish lids), while 厘 is common in measurements and 厗 is extremely rare.

厣 is a technical term in biology and zoology, often found in texts about mollusks or shellfish to describe the operculum—a hard lid that closes the shell opening. Common words are 螺厣 (snail operculum), 厣甲 (the lid of a shellfish), and 闭厣 (to close the operculum). It is rarely used in everyday conversation but appears in scientific descriptions or traditional Chinese medicine when discussing certain shell materials.

Common words containing 厣 include: 螺厣 (luó yǎn) — operculum (snail shell lid); 厣甲 (yǎn jiǎ) — operculum (of a snail or shellfish); 闭厣 (bì yǎn) — to close the operculum (of a shell).