POS Classification vs MeCab
The same token can carry different POS labels in MeCab and Suzume. The examples below group those differences by lexical category, predicate structure, and context; the final section explains how the two taxonomies relate.
Looking for token boundary differences?
This page covers how tokens are labeled. For where token boundaries differ — merging, splitting, and normalization — see Differences from MeCab.
Reading the comparisons
The MeCab row uses Japanese POS names; the Suzume row uses public API tags with Japanese labels. All examples use the shared comparison baseline.
Lexical categories
Adjective-Derived よく
MeCab lexicalizes よく as an adverb. Suzume assigns ADJ as the continuative form of よい:
Ordinary adjective continuative forms such as 美しく are omitted because current MeCab also classifies them as adjectives.
Pronoun Recognition
MeCab classifies many pronouns as plain nouns. Suzume assigns PRON:
Applies to: あなた, みんな, 皆, 某, 拙者, 我輩, 彼女, 奴, 我, わし, いくら (interrogative)
Suzume also assigns PRON to the colloquial pronouns どいつ, こいつ, そいつ, and あいつ. If a MeCab dictionary variant splits the surface, the normalization pipeline restores one token.
Colloquial あんた, おめえ, and てめえ, and literary いずこ, are also PRON. The lemma of おめえ is おまえ.
Greeting Interjections
Suzume keeps greeting expressions under INTJ and marks them INTJ_挨拶. This includes ありがとう, おめでとう, ごめん, and すみません, even when a phrase comes before the greeting:
ありがとう→ありがとう(INTJ, extendedPos: INTJ_挨拶)心からありがとう→心(NOUN) / から(PARTICLE) / ありがとう(INTJ, extendedPos: INTJ_挨拶)
おつかれさま uses the same subtype. Ordinary exclamations such as ああ and おい remain INTJ without the greeting subtype.
Na-Adjective Recognition
MeCab classifies na-adjective stems as nouns (形容動詞語幹). Suzume recognizes them as adjectives:
In attributive contexts, examples include きれい, しずか, 穏やか, 元気, しんちょう, ありきたり, 無限, and 滅多. Ambiguous nominal readings are resolved from context.
Some stems remain NOUN in isolation: マジ, 乙, 公式, 積極, 傍若無人. Context can change the classification; for example, マジで uses ADJ for マジ.
Suffix Recognition
Some productive derivational suffixes receive the dedicated SUFFIX tag, and the stem keeps its own class and lemma. Others form a single nominal or adjectival search unit.
Nominalizer さ turns an adjective into a noun; Suzume keeps the adjective stem visible:
The same nominalizer follows the stem of らしい. In 本らしさ, Suzume assigns らし the auxiliary subtype AUX_推定語幹 and treats さ as a suffix; the IPA dictionary labels this さ as a sentence-final particle.
Trace suffix っけ is distinct from the sentence-final particle with the same spelling. After a nominal host in 飾りっけ, Suzume uses SUFFIX_気配:
The property nominalizer み stays with its adjective stem as one noun: 眠み(NOUN) and 無理み(NOUN).
X的 + な is treated as one na-adjective:
For suffixes that change token boundaries, such as 中, 抜き, and 建て, see Compounds, Quantities, and Names.
Deverbal Nouns
A verb continuative used as a noun keeps NOUN, even where a MeCab dictionary labels it a verb form:
Other deverbal forms are context-dependent; see 違い and 推し in the per-word table below.
Onomatopoeia and Mimetics
MeCab classifies katakana onomatopoeia (reduplication patterns) as nouns. Suzume recognizes them as adverbs:
Mimetics ending in っと are also kept whole as adverbs:
Hiragana repetitions also stay whole as ADV, including voiced repetitions such as はるばる and ほのぼの. Kanji-led repetitions such as 恐る恐る and 泣き泣き receive the same tag. A following adverbial と remains separate: しっとりと gives しっとり(ADV) / と(PARTICLE).
Predicates and auxiliaries
て-Form Auxiliaries
After the connective て/で, subsidiary verbs lose their independent meaning and receive AUX. Suzume applies this consistently across the whole construction family, where MeCab labels them 動詞 (usually with the 非自立 subcategory).
Progressive いる and trial みる — the independent verbs いる and 見る remain VERB elsewhere:
Giving and receiving auxiliaries くれる, あげる, もらう:
Completive しまう and its contraction ちゃう:
Contracted progressive てる/でる — each contraction keeps its surface form as the auxiliary lemma:
For てる, 食べてる yields 食べ(VERB, lemma: 食べる) / てる(AUX, lemma: てる).
Humble いただける in polite requests stays VERB; the following polite or negative forms are auxiliaries:
Resultative てある is the exception — ある keeps its existential meaning and remains VERB:
Purpose Expressions and Subsidiary ゆく
A hiragana verb stem before に plus a motion verb remains VERB in a purpose expression. In literary "verb stem + ゆく/いく" expressions, the second element is treated as a verb.
Restoring Hiragana Verb Inflections
When MeCab analyzes a short pure-hiragana nasal sound change as a noun, Suzume restores the verb and its lemma from the following だ/で and the inflection pattern. A Godan-wa verb whose final う was split as an auxiliary is also restored to one token.
Verb Stems in Honorific Requests
In "お/ご + verb stem + くださる/いたす/いただく" constructions, a stem that is homographic with a noun is restored to a verb from the grammatical structure.
で+ある Copula Handling
Suzume applies context-aware classification for the copula である pattern:
ない Context-Dependent Classification
Suzume assigns ADJ rather than AUX to ない/なく/なかっ when they function as an existence adjective:
existence negation
negation auxiliary
lexical adjective
The continuative なく follows the same distinction. It is AUX after a verb or passive/causative stem, but ADJ after an adjective continuative or in an independent absence expression:
Contracted Hypotheticals
Suzume recognizes colloquial contracted hypothetical forms as one inflected predicate while preserving the lemma:
Verb forms report VERB_仮定縮約 in extendedPos; adjective forms keep their adjective inflection category.
Colloquial Verb Contractions
In 食べらんない, the contracted potential auxiliary keeps its own boundary: 食べ(VERB) / らん(AUX, lemma: られる) / ない(AUX). Before prohibitive な, a verb ending contracted from る to ん stays part of the verb: ふざけんなよ gives ふざけん(VERB, lemma: ふざける) / な(PARTICLE) / よ(PARTICLE).
Particles and function words
Particle Classification
MeCab classifies certain particles as nouns in some contexts. Suzume applies context-aware classification for 30+ particles:
The nominalizer の functions as a particle here, not a noun. Suzume classifies such cases as particles.
Colloquial Copulas and Particles
Colloquial copulas and particles that dictionary taxonomies handle unevenly are normalized to consistent tags:
| Example | Word | Suzume | Role |
|---|---|---|---|
| いいっすね | っす | AUX (lemma: です) | Casual copula |
| いいじゃん | じゃん | PARTICLE | Colloquial sentence-final particle |
| 夢みたい | みたい | AUX | Similative auxiliary |
| 私なんか | なんか | PARTICLE | Deprecatory/exemplifying particle |
| 英語はおろか | おろか | PARTICLE | "Let alone" particle |
| そうや | や | AUX (lemma: だ) | Regional copula |
The casual copula follows the same boundaries as です: マジっすか gives マジ(NOUN) / っす(AUX, lemma: です) / か(PARTICLE), and そうっした gives そう(ADV) / っし(AUX, lemma: です) / た(AUX).
Suzume recognizes some regional predicate tails and particles in context. Examples include あかん and へん as AUX, ねん and さかい as PARTICLE, and the polite copula どす as AUX. These are grammatical labels, not a claim that every dialectal expression is covered.
Context and taxonomy
Context-Dependent POS
Suzume applies context-aware POS classification for several ambiguous words:
そう: AUX after a predicate in an appearance expression (しまいそう, 降りそう), and ADV when standalone or before a copula (そうだ).
でも: PARTICLE after a host, but CONJ at the start of a clause:
いかが: ADJ before a copula (いかがですか) and ADV otherwise.
大変: ADJ before the attributive copula な and before だ/です; it is ADV in adverbial use (大変良い) and in isolation.
どう: ADV before a copula (どうだ) and in other adverbial uses, including どうする and かどうか:
Without a preceding predicate, the fragment かどうか can be misread as a verb. Supply the complete clause when analyzing this construction.
よう: the volitional う after a 未然形 is AUX. In ような, このような方法, and 夢のような話だ, よう is the formal noun NOUN and な is copular AUX with lemma だ:
なら: the standalone conditional stays a particle; before a negative (ならない, ならなかった), it parses as the verb なる.
Per-Word POS Differences
The following words are classified differently between MeCab and Suzume:
| Word | MeCab | Suzume | Reason |
|---|---|---|---|
| なら | 接続詞 | PARTICLE / VERB (文脈依存) | Conditional particle when standalone; parsed as the verb なる before negatives |
| 違い | 名詞・ナイ形容詞語幹 | VERB / NOUN (文脈依存) | Standalone is VERB (lemma: 違う); 違いない, 違いがある, and modified nominal uses are NOUN |
| 推し | 動詞 | NOUN (名詞) | Modern noun usage |
| 嫌い | 動詞 | ADJ (形容詞) | Na-adjective |
| 大変 | 名詞・形容動詞語幹 | ADJ / ADV (文脈依存) | ADJ before な/だ/です; ADV in adverbial or isolated use |
| 超 | 接頭詞 | NOUN (名詞) | Modern usage |
| びっくり | 名詞・サ変接続 | ADV (副詞) | Adverb usage |
| なるほど | 感動詞 | ADV (副詞) | Adverb usage |
| たくさん | 名詞・副詞可能 | ADV (副詞) | Adverb usage |
| いずれ | 名詞・代名詞 | ADV (副詞) | Adverb usage |
| じゃん | 接続詞 + 終助詞 | PARTICLE (助詞) | Colloquial sentence-final particle |
| よう | 感動詞 | AUX / NOUN (文脈依存) | Volitional う after 未然形 (見よ + う); formal noun in contextual ように / ような constructions |
| 時々 | 副詞 | NOUN (名詞) | Noun usage |
| 遥か | 副詞 | ADJ (形容詞) | Na-adjective |
| どう | 副詞 | ADV (副詞) | Adverb before a copula and elsewhere |
| まじ | 助動詞 | ADJ (形容詞) | まじ is an adjective; katakana マジ is NOUN alone but ADJ in contexts such as マジで |
| っていう | 助詞 | DET (連体詞) | Determiner |
| という | 助詞 | DET (連体詞) | Determiner |
| といった | 助詞 | DET (連体詞) | Quotative determiner (DET_引用) |
| まして | 副詞 | CONJ (接続詞) | Conjunction |
| いわば | 副詞 | CONJ (接続詞) | Conjunction (言わば) |
| その後 | 名詞・副詞可能 | ADV (副詞) | Adverb usage |
| しどろもどろ | 名詞・形容動詞語幹 | ADV (副詞) | Adverb usage |
寒し is not a broad-POS difference: both analyzers label it as an adjective, and Suzume returns the lemma 寒い.
POS Granularity
Suzume's basic POS (pos) uses a simpler tag set than MeCab's detailed subcategories.
| MeCab | Suzume pos |
|---|---|
| 名詞,一般 | NOUN |
| 名詞,固有名詞,地域 | NOUN |
| 名詞,サ変接続 | NOUN |
| 名詞,副詞可能 | NOUN |
| 動詞,自立 | VERB |
| 動詞,非自立 | AUX (default) |
The 動詞,非自立 subcategory maps to AUX by default. A small set of subsidiary verbs (すぎる, くださる, あげる, くれる, もらう, いく, いる, …) is not blanket-mapped: they stay VERB in independent use, and context rules such as the て-form classification above assign AUX where they act as auxiliaries.
The extendedPos field provides Suzume's own finer-grained taxonomy. The following rows show rough MeCab feature analogues, but a MeCab label does not by itself cause the corresponding Suzume value; dictionary flags, structure, and context determine it.
| Rough MeCab feature analogue | Suzume extendedPos |
|---|---|
| 名詞,固有名詞 | NOUN_固有 |
| 名詞,固有名詞,人名 | NOUN_名 / NOUN_姓 |
| 名詞,数 | NOUN_数 |
| 名詞,サ変接続 | NOUN_転成 |
| 名詞,形式名詞 | NOUN_形式 |
| 動詞,連用形 | VERB_連用 |
| 動詞,未然形 | VERB_未然 |
| 動詞, 活用形=仮定縮約1 | VERB_仮定縮約 |
| 形容詞,連用形 | ADJ_連用 |
| 形容動詞語幹 | ADJ_NA |
| 助動詞, 活用型=文語・キ | AUX_文語過去キ |
| 助詞,格助詞 | PART_格 |
| 助詞,係助詞 | PART_係 |
extendedPos is not a drop-in replacement for MeCab dictionary features. For example, a proper noun or number can remain plain NOUN when Suzume has no dictionary or structural evidence for a narrower class. See the API Reference ExtendedPOS section for the full list.