Meaning
The kanji 燃 (もえる, もやす, ねん) primarily means "to burn," "to blaze," "to glow," or "to ignite." It's a versatile character used to describe both something burning on its own (intransitive) and the act of setting something on fire or burning it (transitive).
The kanji's origin is quite illustrative. On the left is the radical 火 (ひ), meaning "fire," which clearly signals its connection to fire. The right component, 然 (ぜん, ねん), provides the phonetic reading ねん, but it also adds a semantic nuance. Originally, 然 depicted a dog being roasted over a fire, and thus came to mean "to burn" or "thus, naturally."
When combined with the explicit fire radical 火, 然 reinforces the idea of something naturally or intensely burning, making 燃 a powerful representation of combustion. Therefore, you can think of 燃 as "fire that is burning" or "to burn naturally/thus."
The kanji 燃 has 16 strokes. It is a Jōyō kanji (常用漢字), meaning it's part of the standard set of characters taught in Japanese schools and used in everyday life. While essential for JLPT N2, it isn't assigned a specific primary school grade. This means it's typically learned in secondary education or through general study.
Readings
On'yomi (音読み) — Chinese-derived readings
The On'yomi (音読み), or Chinese-derived reading, for 燃 is:
ネン (NEN): You'll primarily find this reading in compound words, especially those with scientific, technical, or formal meanings related to combustion, fuel, or flammability.
燃焼 (nenshō) — combustion, burning. This term refers to the chemical process of burning. For example, 物の燃焼には酸素が必要です。(Mono no nenshō ni wa sanso ga hitsuyō desu.) — For combustion to occur, oxygen is necessary.
燃料 (nenryō) — fuel. This refers to any material that is burned to produce energy. For instance, 車の燃料が少なくなってきた。(Kuruma no nenryō ga sukunaku natte kita.) — The car's fuel is running low.
可燃 (kanen) — combustible, flammable. This describes something that can easily catch fire. For example, 可燃ごみは指定の袋に入れてください。(Kanen gomi wa shitei no fukuro ni irete kudasai.) — Please put combustible waste in the designated bag.
不燃 (funen) — non-combustible, non-flammable. This describes something that does not easily catch fire. For example, 不燃ごみはこちらの箱へ。(Funen gomi wa kochira no hako e.) — Non-combustible waste goes in this box.
Kun'yomi (訓読み) — Native Japanese readings
The Kun'yomi (訓読み), or native Japanese readings, for 燃 are:
も.える (mo.eru): This is the intransitive verb form, meaning "to burn," "to blaze," or "to glow." Use it when something itself is burning.
燃える (moeru) — to burn, to blaze. For example, 薪がよく燃える。(Maki ga yoku moeru.) — The firewood burns well.
心が燃える (kokoro ga moeru) — one's heart burns (with passion or excitement). For example, 彼女は勝利への情熱で心が燃えていた。(Kanojo wa shōri e no jōnetsu de kokoro ga moete ita.) — Her heart was burning with passion for victory.
燃え上がる (moeagaru) — to flare up, to burst into flames. For example, 火が勢いよく燃え上がった。(Hi ga ikioi yoku moeagatta.) — The fire flared up fiercely.
も.やす (mo.yasu): This is the transitive verb form, meaning "to burn (something)" or "to set fire to (something)." Use it when you burn something else.
燃やす (moyasu) — to burn (something). For example, 古いごみを燃やす。(Furui gomi o moyasu.) — To burn old trash.
エネルギーを燃やす (enerugī o moyasu) — to burn energy (e.g., calories). For example, 運動してカロリーを燃やす。(Undō shite karorī o moyasu.) — To burn calories through exercise.
も.す (mo.su): This is another transitive verb form, also meaning "to burn (something)." While technically correct, it's generally less common in modern Japanese compared to 燃やす, often appearing in specific contexts or older texts.
燃す (mosu) — to burn (something). For example, 紙を燃す。(Kami o mosu.) — To burn paper. (While understandable, 燃やす is more frequently used in this context.)
Common Words & Compounds
Here are some common words and compounds using 燃, categorized by theme for easier understanding:
Fire and Combustion Related:
- 燃焼 (nenshō) — combustion, burning
- 燃料 (nenryō) — fuel
- 可燃 (kanen) — combustible, flammable
- 不燃 (funen) — non-combustible, non-flammable
- 可燃物 (kanenbutsu) — combustible material
- 不燃物 (funenbutsu) — non-combustible material
- 助燃剤 (jonenzai) — combustion promoter, accelerant
- 燃焼効率 (nenshō kōritsu) — combustion efficiency
Action and State Related:
- 燃え尽きる (moetsukiru) — to burn out, to burn to ashes (often used figuratively for exhaustion)
- 燃え盛る (moesakaru) — to burn fiercely, to blaze up
- 燃費 (nenpi) — fuel consumption (efficiency of a vehicle)
- 燃え上がる (moeagaru) — to flare up, to burst into flames
- 燃え広がる (moehirogaru) — to spread (fire)
Figurative and Emotional Uses:
- 情熱を燃やす (jōnetsu o moyasu) — to burn with passion
- 闘志を燃やす (tōshi o moyasu) — to be fired with fighting spirit, to burn with ambition
- 夢を燃やす (yume o moyasu) — to burn with desire for a dream
Example Sentences
薪が勢いよく燃えている。
Maki ga ikioi yoku moete iru.
The firewood is burning fiercely.
古い書類を燃やすことにした。
Furui shorui o moyasu koto ni shita.
I decided to burn the old documents.
工場では大量の燃料が燃焼されている。
Kōjō de wa tairyō no nenryō ga nenshō sarete iru.
Large amounts of fuel are burned in the factory.
その木は湿っていて、なかなか燃えなかった。
Sono ki wa shimette ite, nakanaka moenakatta.
That wood was damp, so it didn't burn easily.
彼は新しい挑戦に情熱を燃やしている。
Kare wa atarashii chōsen ni jōnetsu o moyashite iru.
He is burning with passion for a new challenge.
この車は燃費が良くて、ガソリンをあまり燃やさない。
Kono kuruma wa nenpi ga yokute, gasorin o amari moyasanai.
This car has good fuel efficiency and doesn't burn much gasoline.
可燃ごみと不燃ごみの分別は大切だ。
Kanen gomi to funen gomi no bunbetsu wa taisetsu da.
Sorting combustible and non-combustible waste is important.
運動することで、体の中の脂肪を効率的に燃やすことができる。
Undō suru koto de, karada no naka no shibō o kōritsuteki ni moyasu koto ga dekiru.
Exercising allows you to efficiently burn body fat.
彼は目標に向かって闘志を燃やし、決して諦めなかった。
Kare wa mokuhyō ni mukatte tōshi o moyashi, kesshite akiramenakatta.
He burned with fighting spirit toward his goal, never giving up.
Memory Tip
To remember 燃, let's break it down into its components. On the left is the radical 火 (hi), meaning "fire." The right side is 然 (zen, nen). This component provides the on'yomi ねん and also conveys the idea of "thus" or "naturally." You can visualize this as "A fire (火) that is naturally (然) burning."
Alternatively, imagine a campfire: the fire radical is clear on the left. The right side, 然, can be seen as fire burning, leaving ash (the top part) and producing smoke (the bottom part), indicating the burning process. So, it represents something that 'naturally burns' with fire.