Not used as an ordinary word in modern Chinese; it survives as a surname and in classical lines about trusting or relying on something. It is the speech radical 讠 plus phonetic 甚.
register
Classical and literary; today seen mostly as a family name, not in everyday speech.
The left-side speech radical, 言 in compact form. It supplies the meaning, since trusting a statement is an act of words, grouping the word with 诚 and 信.
