Part 6 · Reading real Japanese · Lesson 63
Grammar words decoded: jargon, auxiliary verbs and why guides disagree
What the technical words mean, how Japanese school grammar names things (and why other guides name them differently), what an auxiliary verb is, why Japanese has no infinitive, and how words are built by gluing endings together.
Once you read a second or third grammar guide, you will find that they disagree on names. One calls 食べない a "negative form". Another calls ない an "auxiliary verb". A third says 食べ is a "stem". They are all describing the same word. This lesson gives you the vocabulary to compare them.
The jargon, in plain English
| Term | Meaning | Example |
|---|---|---|
| noun | thing, concept | 猫, 本 |
| verb | action or event word | 食べる, 行く |
| adjective | describing word | 高い, 静か |
| adverb | describes a verb or adjective | ゆっくり, とても |
| particle | small word that tags a noun | は, が, を |
| predicate | the word (or phrase) that closes the sentence | 食べる, 高い, 学生だ |
| subject | the thing that does or is | 猫が |
| topic | what the sentence is about | 猫は |
| object | the thing acted on | 魚を |
| copula | the "is" word | だ, です |
| clause | a sentence-like unit inside a bigger sentence | 昨日買った |
| conjugation | the changes a word makes | 食べる → 食べた |
| stem | the part that stays when endings change | 食べ |
| nominalizer | makes a clause into a noun | の, こと |
| transitive | takes an object | 開ける |
| intransitive | no object | 開く |
| register | politeness and style level | plain, polite, keigo |
Japanese has no infinitive
English has "to eat" (the infinitive): a form with no tense, no subject, and no mood, used when a verb is the name of an action. Japanese has no equivalent. What you find in a dictionary (食べる) is a real finite form: a plain, present/future-tense verb, usable as a complete sentence ("I eat / will eat"). So "the dictionary form" is not an infinitive. It is the plain non-past form that happens to be listed.
When an English infinitive is needed ("I want to eat"), Japanese uses the stem (食べたい), the て-form (食べてほしい), or a nominalized clause (食べるのが好き).
How Japanese builds words: gluing
Japanese is called agglutinative: words are built by gluing endings onto a stem, each ending doing one job. English mixes meanings into single words (went = go + past), and Latin or Spanish packs several meanings into one ending (hablaré = I-will-speak). Japanese lines them up:
Each piece does one thing, and the order is predictable. That is why the earlier lessons felt like building with blocks. When you meet a long word, peel it from the right.
School grammar and the six forms
Japanese schools teach 学校文法 (school grammar). It is the grammar most dictionaries, textbooks for Japanese children, and the JLPT-style Japanese reference books use. Its basic idea is that every verb has six conjugation forms (活用形), named by their typical use:
| Name | Typical use | 書く | 食べる |
|---|---|---|---|
| 未然形 (mizenkei, "not yet") | before ない, せる, れる, う/よう | 書か / 書こ | 食べ |
| 連用形 (ren'youkei) | before ます, た, て, ながら | 書き / 書い | 食べ |
| 終止形 (shuushikei) | ends a sentence | 書く | 食べる |
| 連体形 (rentaikei) | before a noun | 書く | 食べる |
| 仮定形 (kateikei) | before ば | 書け | 食べれ |
| 命令形 (meireikei) | commands | 書け | 食べろ |
Notice the logic. Instead of "the negative form" it says "the form that goes before ない". Western-style guides (including this course) give names by meaning instead: negative, polite, past, te-form. Both describe the same facts. The school-grammar system explains why 書か, 書き, 書く, 書け, 書こ form a pattern: the five vowels あ, い, う, え, お.
What is an auxiliary verb?
In school grammar, the endings that attach to a verb are mostly auxiliary verbs (助動詞, jodōshi). They include:
| Auxiliary | Job | In this course |
|---|---|---|
| ない | negative | "negative form" |
| ます | polite | "polite form" |
| た | past | "past form" |
| れる / られる | passive, potential, honorific | "passive" |
| せる / させる | causative | "causative" |
| たい | want | "want form" |
| う / よう | let's, intend | "volitional" |
| だ / です | is | "copula" |
| らしい | apparently | "hearsay" |
The same word is thus "a verb ending" or "an auxiliary verb" depending on the guide. What matters is that they are all small units with one job, glued on in a fixed order.
By contrast, helper verbs in the Western sense (いる in 食べている, しまう in 食べてしまう) are full verbs used after the て-form. School grammar calls these 補助動詞 (supplementary verbs).
Parts of speech in school grammar
School grammar sorts words into ten classes:
| Class | Japanese | Examples |
|---|---|---|
| noun | 名詞 | 猫, 学校 |
| verb | 動詞 | 食べる |
| i-adjective | 形容詞 | 高い |
| na-adjective | 形容動詞 | 静かだ |
| adnominal | 連体詞 | この, あの, 大きな, いわゆる |
| adverb | 副詞 | ゆっくり, とても |
| conjunction | 接続詞 | しかし, だから |
| interjection | 感動詞 | ああ, はい, もしもし |
| auxiliary verb | 助動詞 | ない, ます, た |
| particle | 助詞 | は, が, を |
The odd one is 連体詞 (adnominal): words that only ever come before a noun and cannot be used alone. この (this), その, あの, 大きな (big), 小さな (small), ある (a certain), いわゆる (so-called). They are not adjectives because they do not conjugate.
Particles are split into case particles (が, を, に), binding particles (は, も), conjunctive particles (て, ば, から), and sentence-final particles (ね, よ).
Why guides disagree
There are three reasons.
- Different schools. Japanese school grammar, Western-style learner grammar, and academic linguistics each choose their own names.
- Different goals. A guide for beginners wants to say "negative form" and move on. A guide for linguists wants to explain why.
- Real ambiguity. Is だ an auxiliary verb or a copula verb? Is ない an adjective or an auxiliary? Linguists argue, and there is no single right answer.
The best response: do not fight the terms. When a guide uses a name you don't know, translate it into the thing it describes, and carry on.
Why parsing is hard
Parsing a Japanese sentence by machine (or by eye) is harder than in English because:
- There are no spaces. You decide where words begin and end.
- Words carry long strings of endings. 食べさせられたくなかった is one word with six meaningful parts.
- Dictionary tools disagree. Tools like MeCab (used by many dictionaries and pop-up readers) split text into morphemes using a dictionary and statistics. One may split 食べている as one unit and another as 食べ + て + いる.
- Subjects vanish. The grammar of what to supply is in context.
If your pop-up dictionary breaks a word oddly, it isn't you. Check whether a verb plus endings has been cut into pieces.
Archaic or "poetic" forms
Old grammar names also survive in writing: the adjective ending -き (美しき姫: a beautiful princess), -し (美し), -ぬ (知らぬ: don't know). They are covered in the lesson on old-fashioned Japanese.
Longer sentences
Take apart a long word piece by piece, naming each part. The point is not the terms but being able to peel from the right.
Key points
- A predicate closes the sentence; a particle tags a noun; a clause is a sentence inside a sentence.
- Japanese has no infinitive. The dictionary form is a plain present/future verb.
- Japanese is agglutinative: endings are glued on, one job each.
- School grammar's six forms (未然形, 連用形, 終止形, 連体形, 仮定形, 命令形) name forms by use.
- An auxiliary verb (助動詞) is an ending like ない, ます, た, れる, せる, たい.
- Guides disagree on names, not on facts.