noun which may take the genitive case particle 'no', noun
Used as a noun or with の to mean 'second' in order, rank, or sequence. Common in compounds like 二次試験 (second-stage exam).
二次試験は来週行われます。
The second-stage exam will be held next week.
noun-modifying (irregular)
Prenominal use (adj-f) meaning 'secondary' or 'of lesser importance'. Often in fixed terms like 二次的な問題 (secondary issue).
それは二次的な問題に過ぎない。
That is merely a secondary issue.
noun-modifying (irregular)
quadratic; second-order
Mathematics term; used prenominally in phrases like 二次関数 (quadratic function) or 二次方程式 (quadratic equation).
二次関数のグラフを描いてください。
Please draw the graph of the quadratic function.
noun which may take the genitive case particle 'no'
fictional; two-dimensional; drawn
Abbreviation of 二次元 (two-dimensional), used in otaku culture to refer to anime, manga, or fictional characters as opposed to real life (三次元). Often written as 虹 in niche contexts.
See also: 二次元
彼は二次のキャラクターにしか興味がない。
He is only interested in fictional characters.
二次元 is the full term for 'two-dimensional', while 二次 is its abbreviation used in otaku slang.
三次 means 'third' or 'tertiary', and in otaku contexts, 三次元 (three-dimensional) refers to the real world.
Compound of 二 (two) and 次 (order, next). The otaku slang sense is a shortening of 二次元 (two-dimensional).