Rare in everyday speech; chiefly a traditional-medicine term, usually inside the compound 痈疽 (abscesses and ulcers). Built from the sickness radical 疒 plus phonetic 用; the traditional form 癰 used 雍 for the sound.
The sickness radical, a bed leaned on its side by an unwell person. It puts 痈 in the disease family alongside 病 and 痛, flagging the word as a bodily ailment.
