ましん 真っ芯 LinksSentence search for 真っ芯Sentence search for まっしんSentence search for 真っ心Kanji details for 真 and 芯Edit in JMdict Noun1. dead center (of a baseball bat); sweet spotSee also 真芯Other forms真っ心 【まっしん】Notes真っ心: Rarely-used kanji form. Discussions Log in to talk about this word.