Are there clear definitions for Japanese verb “roots,” “bases,” and “stems”? In books, online, and in classes, I encounter conflicting definitions, as described below.
ROOTS https://www.tofugu.com/japanese-grammar/verb-conjugation-groups/, accessed 6 Sept. 2022, defines “root” of both godan and ichidan verbs as “the part of the verb that (almost always) remains the same when the verb is conjugated. [Re.] 聞く… The part that remains the same in all the conjugations shown is kik, so it is the root.” The NihonShock website, https://nihonshock.com/2013/09/the-bases-of-japanese-verbs/, accessed 6 Sept. 2022, defines roots similarly: 上一段活用動詞 (見る, 用いる, Etc.) (roots end in i-) 下一段活用動詞 (食べる, 求める, Etc.) (roots end in e-) 五段活用動詞 (買う, 待つ, Etc.) (roots end in consonants) サ変活用動詞 （する） (root is s-) カ変活用動詞 （来る） (root is k-) However, as noted below, some people define this form as the verb ”base” or “stem.” Intensive Course in Japanese, Elementary, v. 3, from the Japanese Language Promotion Center, 1970, p. 47, says that for godan verbs, “the final syllable of the verb root takes the following different forms: かく kaku ki ku ka ko ke…” Yet a few pages earlier it states that the “stem” of かく is かき.
BASES Some say bases are synonymous with stems, but seem to define stems differently. For example, https://www.wasabi-jpn.com/japanese-grammar/japanese-verbs-u-verbs-and-ru-verbs-and-conjugation/, accessed 6 Sept. 2022, says: “Japanese verbs always contain two parts: a verb base and a suffix. Grammatically, verb bases are called ‘stems.’ … 見る, the stem is “mi” and the suffix is ‘ru.’ ” Since what precedes godan suffixes changes, this author must conceive five godan bases/stems. Similarly, the NihonShock website refers to a “simplified 7 base system”: ~A 動か 食べ し(する） こ(来る） ~I 動き 食べ し き ~U 動く 食べる する 来る ~E 動け 食べれ すれ くれ ~OU 動こう 食べよう しよう 来よう ~TE 動いて 食べて して きて ~TA 動いた 食べた した きた Under the heading Verb Bases, Wikipedia states, “Conjugable words … are traditionally considered to have six possible conjugational stems or bases (活用形, katsuyōkei, literally "conjugation forms") . …Verb bases function as the necessary stem forms to which inflectional suffixes attach. …With godan verbs, the base is derived by shifting the final kana along the respective vowel row of the gojūon kana table. With ichidan verbs, the base is derived by removing or replacing the final る (ru) kana.” A former teacher told me that the verb base and stem are different. She said that the base is created by removing う from the dictionary form. “For example, with 行く, remove う. Just "ik" remains; it is the verb base.” Others would call that form a "root."
STEMS Many sources seem to agree that godan “stems” are formed by changing the final kana of a verb’s dictionary form to the associated kana ending in い (だす→ だし). Others create the same “stem” by removing –ます from the polite non-past affirmative form (Genki, 2nd ed., v. 1, pp. 151, 254). These sources do not mention godan forms such as ださ– or だせ– in their “stem” definitions, leaving it unclear whether these sources consider only –ます stems to be “stems.” (These sources say that ichidan stems are formed by removing –る from the dictionary form [たべる → たべ] ). Naganuma’s Basic Japanese Course: Grammar and Glossary, rev. ed., 1970, p. 23 specifies that the stem of godan verbs “ends in five different vowels or a combination of a consonant and vowels in the order of a, i,u, e, and o.” But the book almost immediately continues by referring to these five forms as Base I, Base II, etc., apparently considering “stem” and “base” to be synonyms.
Meanwhile https://www.kanshudo.com/grammar/stem, accessed 6 Sept. 2022, says, “The term 'verb stem', also known as 'masu stem', … refers to the base part of the verb…. The easiest way to identify the stem … is to remove the ‘ます’…. The part of the verb that remains is the verb stem.” So this source also equates “base” and “stem,” but restricts its definition of stem to the –ます stem.
The Complete Japanese Verb Guide by The Hiroo Japanese Center, 1989 and ‘91, pp. 10, 11, says that dropping the final う from the dictionary form of godan verbs (and the final るof ichidan verbs) creates their stems. As noted above, this is how some sources define “root.” Intensive Course in Japanese, Elementary, v. 3, 1970, pp. 40-48, agrees that a verb stem is “that part of a verb which always remains the same,” but then shows many “stems” that change (かき from かく, はなし from はなす).
Wikipedia begins, “[T]he verb stem remains invariant among all conjugations” but continues, “The conjugational stem can span all five rows of the gojūon kana table.” In that case, the stem cannot remain invariant; and, as noted above, Wikipedia equates “stems” with “bases.”
Probably numerous additional citations could be added, but you can see the confusion. Are these apparently conflicting definitions because: • There are no precise definitions, causing people to deconstruct verbs by different systems? • Terms vary with the background of the author and/or perceived students/readers? • Some definitions simply are not worded well? I would be very appreciative of clarity!