I first started studying Japanese the summer after my first year of college. I was still promising my parents that I would take the med school prerequisites and eventually become a doctor, but I knew going in to college that all I really wanted to do was learn Japanese. I must have had science on my brain because as I started studying, I set up a scientific analogy in my mind: Much like the electrons in atoms, Japanese adjectives and adverbs use particles to form bonds with neighboring words.
Although not technically a “particle” in the linguistic sense, the most obvious “electron” is い (i), the hiragana character that comes at the end of nearly every adjective. Takai (高い, tall), hikui (低い, low), atsui (暑い, hot), samui (寒い, cold), oishī (おいしい, delicious) and so on.
In my mind, い became the method by which adjectives were able to form bonds with nouns in order to modify them: Takai kabe (高い壁, high wall), hikui reberu (低いレベル, low level), atsui natsu (暑い夏, hot summer), oishī onigiri (おいしいおにぎり, delicious rice ball). Just link the adjective to the front of the noun and you have yourself a perfectly understandable phrase.
Of course nouns can modify other nouns, but because they don’t have い at the end, they require a different particle to provide the connection: の (no). Natsu no hi (夏の日, a summer day), sekai no owari (世界の終わり, the end of the world), ore no pasokon (俺のパソコン, my computer). The second noun is the main noun, and the first is the modifier.
And there are other nouns that are even more adjective-like but require the particle な (na): Tekisetsu na ryō (適切な量, the appropriate amount), benri na hōhō (便利な方法, a convenient method), zannen na kekka (残念な結果, an unfortunate result).
At first these nouns may be difficult to differentiate from ordinary nouns based on their appearance, or from adjectives based on their meanings. Other than the lack of い, many seem like regular adjectives: genki (元気, energetic), shizuka (静か, quiet), kirei (奇麗, beautiful). But you will also find that many are more intangible and conceptual: kenkyo (謙虚, humility/humble), kandai (寛大, generous/generosity), hitsuyō (必要, necessity/necessary), kiken (危険, danger/dangerous).
The particles that help adjectives connect to nouns are volatile and can quickly transform, allowing adjectives to become adverbs and connect with verbs.
Japanese keeps it simple and consistent: い becomes く (ku), while の and な both become に (ni). Thus we have takaku tobu (高く飛ぶ, fly high), yoku shiru (よく知る, know well), nagaku hashiru (長く走る, run far), shizuka ni hanasu (静かに話す, speak quietly), zannen ni omou (残念に思う, regret/feel bad about) and jōzu ni tsukuru (上手に作る, make [something] well).
Even more conveniently, Japanese has the catchall verbs suru (する, to do) and naru (なる, to make) that will link up with almost any adverb. Suru allows us to “make” or “do” something more like the adjective: atsuku suru (熱くする, make something hot/hotter), yowaku suru (弱くする, make something weak), shizuka ni suru (静かにする, be quiet), kirei ni suru (奇麗にする, make something pretty).
Whereas natta (the past tense of naru) is used when something “becomes” more like the adjective on its own: ocha ga tsumetaku natta (お茶が冷たくなった, the tea became cold), kion ga atsuku natta (気温が暑くなった, the temperature got hot), tsūkin ga taihen ni natta (通勤が大変になった, my commute has gotten terrible).
Because every adjective becomes an adverb so simply, they often result in very pleasurable, efficient phrases. My former Japanese roommate was one of 30 to 50 percent of Japanese who suffer alcohol flush reaction when drinking, and she use to lament, “Oishiku nomeru sake wa nai” (「おいしく飲める酒はない」). Thanks to the lovely and seemingly awkward adverb oishiku (おいしく, “deliciously”), this literally translates to “There are no types of alcohol I can drink deliciously.” A more natural translation would be “There are no types of alcohol I enjoy.”
Although adjectives and adverbs may seem simple at first, it’s important to go beyond the dictionary definitions and triangulate the meaning on your own.
Tekitō (適当) is one of the most frequently misunderstood Japanese words. Dictionaries often list the definition as “suitable,” “appropriate,” “proper” or “adequate,” and these words do capture some of the meaning, but one of my friends was baffled when her company instructed her to tekitō ni shinai de kudasai (適当にしないでください) when handling a particularly difficult client. This phrase could be understood as, “Don’t treat the client appropriately”?
What the English definitions above don’t capture is that tekitō includes a subjective interpretation: It should be considered more along the lines, “Don’t treat the client just as you see appropriate; make sure that the company would consider it appropriate as well.”
On the other hand, a boss who delegates properly, has made her desires clear and has selected the right individuals for the job would have no problem telling them, “Tekitō ni shite” (適当にして, Do it as appropriate).
As you begin to put the pieces of Japanese together, hopefully this chemical analogy helps you keep everything straight. You’ll occasionally bump into some oversized “polysaccharides” such as gensenchōshūhyō (源泉徴収表, wage and tax certificate) and maybe even undōkai-junbi-iinkai (運動会準備委員会, sports festival preparation committee) that don’t need any electrons to help them form large compounds, but you’ll be better able to recognize how these words interact with others by noticing the particles that help link them with other words.