疾 is a Chinese hanzi, listed here under the keyword “illness”. It is built from 疒 (sick) and 矢 (arrow). It appears as a component in 5 other characters in this index.
On KumiJi Glyph Explorer, open the parts search and type “sick” + “arrow”. 疾 is among the results, together with every other character containing the same shapes.
Open 疾 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.