忌 is a Chinese hanzi, listed here under the keyword “jealous”. It is built from 己 (self) and 心 (heart). It appears as a component in 4 other characters in this index.
On KumiJi Glyph Explorer, open the parts search and type “self” + “heart”. 忌 is among the results, together with every other character containing the same shapes.
Open 忌 in the interactive kanji search
to expand every part down to its smallest pieces, add your own names and mnemonic stories,
or search for other characters by their parts.