Let's explore the JLPT N1 kanji 凹. This character uniquely embodies its core meaning visually, making it key to understanding shapes, depressions, and even emotional states in Japanese. Whether it's describing scientific terms like optical lenses or everyday occurrences like a dented surface, 凹 is a crucial character.
Meaning
The kanji 凹 (ō) primarily signifies 'concave', 'hollow', 'dent', 'sunken', or 'depressed'. Its meaning is strongly tied to its distinctive visual form, which directly depicts a recessed or hollowed-out shape. Think of looking into a bowl or a dip in the ground; the character 凹 perfectly captures that image.
The origin of 凹 is a remarkable example of a pictograph. Unlike many complex kanji formed from multiple radicals, 凹 stands alone, graphically depicting a depression or a sunken area. The two outer vertical lines and the horizontal line beneath them form an enclosure. Inside, a shorter horizontal line, positioned lower, symbolizes the 'hollow' or 'indentation' within that space. This direct visual representation makes 凹 one of the most iconic and easily recognizable characters in Japanese.
In different contexts, 凹 can describe physical characteristics. For instance, it might refer to a surface that curves inward or an object that has been pushed in. Beyond the physical, when paired with its kun'yomi reading へこむ, it can also metaphorically describe feeling 'depressed' or 'downhearted'. Grasping its visual origin helps immensely in understanding its many applications.
With 5 strokes, 凹 is a Grade 8 kanji in the Japanese school system, meaning students learn it in junior high school. It's also one of the Jōyō Kanji, designated for daily use, making its understanding vital for advanced learners of Japanese.
Readings
On'yomi (音読み) — Chinese-derived readings
The primary On'yomi (Chinese-derived reading) for 凹 is オウ (Ō). You'll typically find this reading in compound words, where 凹 combines with other kanji to form more technical or abstract concepts.
オウ (Ō): This reading is found in terms related to geometry, optics, and general descriptions of unevenness.
凹凸 (ōtotsu) — This is perhaps the most common compound, meaning 'unevenness', 'irregularities', 'concavity and convexity'. It directly contrasts 凹 (concave) with 凸 (convex).
凹面 (ōmen) — Meaning 'concave surface'. This term is frequently used in physics and optics to describe surfaces that curve inward, such as a concave mirror or lens.
凹版 (ōhan) — Refers to 'intaglio printing' or 'gravure printing', a method where the image is incised into a surface.
凹レンズ (ōrenzu) — This compound specifically means 'concave lens', a type of lens that diverges light rays.
Kun'yomi (訓読み) — Native Japanese readings
The Kun'yomi (native Japanese readings) for 凹 are quite versatile. They often appear as verbs or nouns, directly describing the action or state of being concave or dented. These readings offer a more direct and often colloquial connection to the kanji's meaning.
へこむ (hekomu): This is an intransitive verb meaning 'to become dented', 'to sink', 'to cave in', 'to be depressed', or 'to feel dejected'. It describes the state of something becoming concave or an individual feeling down.
缶が凹む (kan ga hekomu) — The can gets dented.
試験に落第して心が凹んだ (shiken ni rakudai shite kokoro ga hekonda) — I failed the exam and felt depressed.
へこます (hekomasu): This is a transitive verb meaning 'to dent (something)', 'to make concave', 'to outdo', or 'to humble'. It describes the action of causing something to become concave or causing someone to feel humbled.
車を凹ます (kuruma o hekomasu) — To dent a car.
相手を凹ます (aite o hekomasu) — To humble one's opponent (colloquial).
くぼむ (kubomu): While often written with 窪む, the meaning of 'to become hollow' or 'to sink in' can also be conceptually represented by 凹む, especially in older texts or specific contexts. For example, 目が凹む could imply sunken eyes.
地面が凹む (jimen ga kubomu) — The ground sinks in / forms a hollow.
Common Words & Compounds
The kanji 凹 is found in many words and compounds, showing its broad application from scientific fields to everyday observations. Here's a selection organized by theme:
General Shapes & Irregularities
凹凸 (ōtotsu) — Unevenness, irregularities, ups and downs. This key term is widely used to describe surfaces that aren't flat.
凹型 (ōgata) — Concave shape, U-shaped. Describes anything with an inward curve or depression.
凹地 / 凹地 (kubochi / ōchi) — A depression, a hollow, low-lying ground. Used in geography and topography to describe landforms.
Optics & Physics
凹面 (ōmen) — Concave surface. Essential for understanding mirrors, lenses, and other optical instruments.
凹レンズ (ōrenzu) — Concave lens. A type of lens that diverges light, used in various optical devices.
凹面鏡 (ōmenkyō) — Concave mirror. A mirror that curves inward, reflecting light to a focal point.
Actions & States (Kun'yomi based)
凹む (hekomu) — To become dented, to sink in, to feel depressed. This verb captures both physical and emotional states.
凹ます (hekomasu) — To dent (something), to make concave, to humble. The transitive counterpart to へこむ.
凹み (hekomi) — A dent, a depression, an indentation. This is the noun form derived from へこむ.
Printing & Manufacturing
凹版 (ōhan) — Intaglio printing, gravure. A printing technique where the image is etched or engraved into a surface.
凹凸加工 (ōtotsu kakō) — Embossing and debossing, texturing. A process to create raised or recessed patterns on a surface.
Example Sentences
車のドアが事故で少し凹んでしまった。
Kuruma no doa ga jiko de sukoshi hekonde shimatta.
The car door got a little dented in the accident.
この地面には大きな凹みがあるため、水がたまりやすい。
Kono jimen ni wa ookina hekomi ga aru tame, mizu ga tamariyasui.
Because there's a big hollow in this ground, water tends to collect easily.
凹レンズは光を拡散させる性質がある。
Ōrenzu wa hikari o kakusan saseru seishitsu ga aru.
A concave lens has the property of diverging light.
長い間座っていたせいで、ソファが少し凹んだ。
Nagai aida suwatteita sei de, sofa ga sukoshi hekonda.
Because I was sitting for a long time, the sofa got a little dented/depressed.
失敗しても絶対に凹まず、次に向かって頑張ろう。
Shippai shite mo zettai ni hekomazu, tsugi ni mukatte ganbarou.
Even if you fail, don't get depressed; let's work hard towards the next one.
彼の発言で、私は気持ちが少し凹んでしまった。
Kare no hatsugen de, watashi wa kimochi ga sukoshi hekonde shimatta.
His remark made me feel a little down.
この道路は凹凸が激しいので、運転には注意が必要だ。
Kono dōro wa ōtotsu ga hageshii node, unten ni wa chūi ga hitsuyō da.
This road is very uneven, so caution is needed when driving.
職人は金槌で金属を巧みに凹まして、芸術的な模様を作った。
Shokunin wa kanazuchi de kinzoku o takumi ni hekomasete, geijutsuteki na moyō o tsukutta.
The craftsman skillfully dented the metal with a hammer to create an artistic pattern.
古い井戸の周りは長年の使用で地面が凹んでいる。
Furui ido no mawari wa naganen no shiyō de jimen ga kubondeiru.
The ground around the old well is hollowed out from years of use.
実験では、光線が凹面鏡に当たると一点に集まることが観察された。
Jikken de wa, kōsen ga ōmenkyō ni ataru to itten ni atsumaru koto ga kansatsu sareta.
In the experiment, it was observed that light rays converge at one point when they hit a concave mirror.
Memory Tip
Recalling the kanji 凹 is straightforward, thanks to its highly illustrative nature. The character perfectly represents its meaning: 'concave' or 'hollow'. Picture the central, shorter horizontal line as the bottom of a pit or depression. The longer outer lines form the edges of this hollowed-out space. It literally looks like a cross-section of a dent or a valley. Whenever you see 凹, visualize a cave entrance, a dented soda can, or a bowl. The inner stroke is 'down' or 'in' compared to the outer structure, effectively conveying the idea of 'sinking in' or 'being depressed'. This makes 凹 one of the most intuitive kanji to remember, resembling a minimalistic drawing of a concave shape.