annoyance; irritation; vexation
Used for a feeling of irritation or frustration, often in the phrase 癪に障る (しゃくにさわる) meaning 'to get on one's nerves'.
His attitude got on my nerves.
abdominal spasms; cramps; convulsions
Dated medical term for abdominal cramps or spasms; now mostly replaced by 腹痛 (ふくつう) or けいれん.
Don't say it in such an irritating way.
In the past, the word 癪 was used to refer to stomach cramps.
impudent; cheeky; saucy
Standard kanji spelling for both senses.
Kana spelling is common in informal writing, especially for the annoyance sense.
The kanji 癪 is a kokuji (Japanese-made character) combining 疒 (sickness) and 積 (accumulate), originally referring to a buildup of something causing abdominal spasms. The irritation sense likely developed from the discomfort associated with such spasms.