suffix, noun
Medical suffix or noun used in compound disease names to indicate a skin eruption or rash, e.g., 梅毒疹 (syphilitic rash). Rarely used as a standalone noun in modern Japanese; usually appears as part of a compound.
See also: 梅毒疹
梅毒疹は感染から数週間後に現れることがある。
A syphilitic rash may appear several weeks after infection.
この薬の副作用として発疹
A skin eruption has been reported as a side effect of this drug.
発疹 is the common word for 'rash' or 'eruption' used in everyday and medical contexts. 疹 is a bound form that appears mainly in compound medical terms.
The kanji 疹 is composed of 疒 (sickness radical) and 㐱 (phonetic component), indicating a skin disease. The reading しん is the on'yomi. The exact historical derivation is uncertain.