nidan conjugation; bigrade conjugation
A classical Japanese verb conjugation class with two base vowels (e.g., 上二段 and 下二段). Used in historical grammar; modern equivalents are 上一段 and 下一段.
Nidan conjugation is one of the conjugations studied in classical grammar.
二段活用は現代語の一段活用のもとになった。
The bigrade conjugation is the origin of the modern monograde conjugation.
upper bigrade conjugation; nidan verb conjugation (classical Japanese)
lower bigrade conjugation
From 二段 (two grades) + 活用 (conjugation), referring to the two distinct vowel stems in classical Japanese verb inflection.