忄是汉字部首，由“心”演变而来。称竖心旁或竖心。古代人认为心脏主管人的思想，故“忄”旁的字多与心理活动有关。
忄 is the radical of Chinese characters, which evolved from “心”. It is called the vertical heart or the vertical heart. Ancient people believed that the heart is in charge of human thoughts, so the words next to “忄” are mostly related to mental activities.
释意
同“心”，用作偏旁。俗称“竖心旁”，简称“竖心”。
书写注意
“忄”的左右点不同:左为“ 左点”,下部稍向左斜;右为侧点 。先写左点，后写右点，最后写垂露竖。左点略低,右点略高。
古籍解释
康熙字典
【卯集上】【心字部】𢛔 ·康熙笔画：0 ·部外笔画：0
《集韵》同懒。字头字从忄从柬。
含有竖心旁的字有：快、悃、懂、怪、情、悄、怕、忙、懒、慌、慢、惜、惊、恨、怦、憎、懈、怏、惯、愣、悔、惶、悼、惭、慷、恍、慨、愉、性、懊、惋、惟、愧、悟、忆、愤、恬、恻、恼、愕、懦、怡、惨、恰、恒、憾、悦、忧、怜、惰、恢、慎、悯、怀等。
Paraphrase
The same “heart”, used as a radical. Commonly known as “Zhuxinbian”, or “Zhuxin” for short.
Write attention
The left and right points of “忄” are different: the left is the “left point”, the lower part is slightly inclined to the left; the right is the side point. Write the left point first, then the right point, and finally write down. The left point is slightly lower and the right point is slightly higher.
Ancient books explained
Kangxi Dictionary
【卯集上】【Heart Word Department】𢛔 ·Kangxi strokes: 0 ·External strokes: 0
“Ji Yun” is the same as lazy. The initials are from the embarrassment from the Cambodian.
The words that contain the vertical heart are: fast, sad, understand, strange, emotional, quiet, afraid, busy, lazy, panic, slow, regret, fright, hate, frustration, hatred, lax, unhappy, accustomed, frustrated, regret, Anxiety, condolences, embarrassment, generosity, embarrassment, generous, pleasure, sex, regret, sorrow, but, ashamed, comprehension, recollection, anger, sorrow, annoyance, sorrow, cowardice, joy, misery, cha, constant, regret, Joy, sorrow, pity, laziness, grace, caution, compassion, compassion, etc.