noun, noun which may take the genitive case particle 'no'
inner thoughts; real intention; one's mind
Refers to what one truly thinks or feels inside, often contrasted with outward expression. Common in phrases like 内心では or 内心ほっとする.
内心では彼の意見に賛成だった。
Inwardly, I agreed with his opinion.
She felt relieved deep down.
noun, adverb
at heart; deep down; on the inside
Adverbial use emphasizing one's true feelings, often with は or で. Similar to sense 1 but used as an adverb.
内心は違うことを考えていた。
Deep down, I was thinking something different.
noun
inner center (geometry)
Mathematics term for the center of an inscribed circle. Rare outside technical contexts.
See also: 外心 (がいしん)
三角形の内心は三つの角の二等分線の交点である。
The incenter of a triangle is the intersection of its three angle bisectors.