Meaning
The kanji 沼 (numa) refers to a 'swamp', 'marsh', 'pond', or 'bog'. It describes a stagnant body of water, typically shallow and rich with vegetation. This distinguishes it from a larger lake (湖) or a smaller, often artificial pond (池).
Essentially, 沼 indicates a natural depression or land area where water collects and drains slowly. This process leads to the accumulation of organic matter and frequently results in muddy conditions.
Its origin helps us understand its meaning better. The left-hand radical, 氵 (sanzui), is the 'water' radical, immediately signaling the kanji's connection to water. The right-hand component is 召 (shō), meaning 'to call' or 'to invite'.
While 召 primarily serves as a phonetic component, providing the kanji its on'yomi reading ショウ, it also subtly contributes to the meaning. You might imagine a swamp or marsh 'beckoning' or 'calling' to those who approach, perhaps with its mysterious depths or the deceptive solidity of its muddy banks. In a more practical sense, 召 can imply something contained or shallow, linking to the nature of a marsh as a contained, shallow body of water. Thus, the kanji visually combines the idea of water with a phonetic hint that also subtly reinforces its characteristic nature.
The kanji 沼 has 8 strokes. It is not assigned a specific elementary school grade (indicated as Grade 0 or S for supplementary/secondary school level). Learners typically encounter it at a more advanced stage, corresponding to the JLPT N1 level.
Readings
On'yomi (音読み) — Chinese-derived readings
The on'yomi reading for 沼 is ショウ (shō). This reading stems from the kanji's original Chinese pronunciation and is typically used when 沼 forms part of a compound word, especially in more formal or technical contexts. While 沼 by itself is almost exclusively read with its kun'yomi, the on'yomi is essential in compound words that describe broader wetland concepts.
- 沼沢 (shōtaku) — This compound combines 沼 (swamp) with 沢 (marsh) to form a more formal term for 'marsh' or 'swamp'. It often refers to extensive wetland areas.
- 湖沼 (koshō) — Meaning 'lakes and marshes,' this term combines 湖 (ko, lake) with 沼 (shō, marsh). It's a common geographical term for various bodies of standing water.
- 沼気 (shōki) — A specialized term for 'marsh gas,' like the methane produced in stagnant swamps.
Kun'yomi (訓読み) — Native Japanese readings
The primary and most common kun'yomi reading for 沼 is ぬま (numa). You'll use this reading when the kanji appears by itself or in compounds that convey its direct, native Japanese meaning. It's the most common reading for referring to a swamp, marsh, or pond in everyday Japanese.
- 沼 (numa) — This is the standalone reading for 'swamp,' 'marsh,' or 'pond,' referring to a natural, often shallow, body of water.
- 泥沼 (doronuma) — Meaning 'quagmire' or 'mud swamp,' this word vividly describes a difficult, inescapable situation. It literally combines 泥 (doro, mud) with 沼 (numa, swamp).
- 沼地 (numachi) — This term refers to 'marshland' or 'swampy ground,' combining 沼 (numa, swamp) with 地 (chi, land) to denote an clean area characterized by swamps.
- 深沼 (fukanuma) — Though less common, this compound meaning 'deep swamp' or 'deep marsh' clearly shows 沼 used in a direct, descriptive native Japanese context.
Common Words & Compounds
To truly grasp 沼, it's helpful to see how it's used in different contexts, from natural landscapes to metaphorical expressions. Below are some common words and compounds:
General Terms for Wetlands:
沼 (numa) — Swamp; marsh; pond. The most fundamental use.
沼地 (numachi) — Marshland; swampy ground. Refers to the area.
沼沢 (shōtaku) — Marsh; swamp. A more formal or technical term for wetlands.
沼沢地 (shōtakuchi) — Wetlands; marshland. Combines the formal 'swamp' with 'land'.
湖沼 (koshō) — Lakes and marshes. A collective term for inland bodies of water.
Specific Types & Conditions:
泥沼 (doronuma) — Quagmire; mud swamp. Literally a swamp of mud, often used figuratively.
温泉沼 (onsennuma) — Hot spring marsh. A specific type of pond or marsh formed by hot springs, for example, some ponds at Jigokudani Monkey Park.
酸性沼 (sanseinuma) — Acidic marsh/pond. A marsh with acidic water, often found in specific geographical areas like high-altitude bogs or volcanic regions.
Figurative & Idiomatic Expressions:
泥沼化 (doronumaka) — To become a quagmire; to get bogged down; to escalate into an intractable situation. This term is often used when a problem, like a difficult negotiation or a long-running dispute, becomes increasingly complex and hard to resolve.
沼に嵌まる (numa ni hamaru) — Literally, 'to fall into a swamp.' Figuratively, it means to get bogged down or stuck in a difficult or undesirable situation, such as getting too deeply involved in a hobby or a bad habit.
Place Names:
大沼 (Ōnuma) — A common place name across Japan. A notable example is Ōnuma Quasi-National Park in Hokkaido, famous for its beautiful lakes and marshy areas.
猿ヶ京沼 (Sarugakkyō Numa) — An example of a specific place name incorporating 沼, indicating a marsh or pond in that area. For instance, the Sarugakkyō Hot Spring area might feature a
猿ヶ京沼.
Example Sentences
その沼の周りには珍しい植物が生えている。
Sono numa no mawari ni wa mezurashii shokubutsu ga haete iru.
Rare plants grow around that marsh.
子供たちは沼地で昆虫を探して遊んでいました。
Kodomo-tachi wa numachi de konchū o sagashite asonde imashita.
The children were playing, searching for insects in the marshland.
深い沼の底には何が潜んでいるのだろうか。
Fukai numa no soko ni wa nani ga hisonde iru no darō ka.
I wonder what lurks at the bottom of the deep swamp.
雨の後、その道は足場が悪い泥沼のようになった。
Ame no ato, sono michi wa ashiba ga warui doronuma no yō ni natta.
After the rain, that road became like a muddy quagmire with poor footing.
探検隊は広大な沼沢地を横断しなければならなかった。
Tanken-tai wa kōdai na shōtakuchi o ōdan shinakereba naranakatta.
The expedition team had to cross vast wetlands.
彼は現在の交渉の状況を「泥沼」と表現した。
Kare wa genzai no kōshō no jōkyō o "doronuma" to hyōgen shita.
He described the current negotiation situation as a "quagmire."
夕暮れ時、湖沼にたくさんの渡り鳥が集まってきた。
Yūgure-doki, koshō ni takusan no wataridori ga atsumatte kita.
At dusk, many migratory birds gathered in the lakes and marshes.
この地域の独特な生態系は、その大きな沼によって維持されている。
Kono chiiki no dokutoku na seitaikei wa, sono ōkina numa ni yotte iji sarete iru.
The unique ecosystem of this region is maintained by its large swamp.
新しい事業は予想以上に泥沼化し、多大な時間と費用を要した。
Atarashii jigyō wa yosō ijō ni doronumaka shi, tadai na jikan to hiyō o yō shita.
The new project became a quagmire more than expected, requiring a great deal of time and expense.
Memory Tip
Here's a tip to help remember 沼: Look at its components. The left side is 氵 (sanzui), the 'water' radical, clearly signaling its connection to water. The right side is 召 (shō), which you can visualize as a 'knife' (刀) over a 'mouth' (口).
Imagine water (氵) that seems to 'call' or 'beckon' (召) you into its shallow, murky depths. Picture a stagnant marsh where the water 'calls' out, inviting creatures, or perhaps even lost travelers, into its contained, often muddy embrace. This visual of something calling from the water can strongly link 召 with the idea of a swamp or marsh.