An unintentional defecation that occurs during the relaxation of the anal sphincter to pass flatulence. It can occur as hard fecal matter but most commonly occurs as diarrhoea. Sharting can also refer to diarrhoea itself, especially the explosive variation.
Etymology:
The word shart is a mix of the words "Shit" and "Fart" which are both slang words for feces and flatulence respectively.