the apical end of the style where deposited pollen enters the pistil
"The botanist carefully examined the stigma to see if the transferred pollen had successfully germinated on its surface."
an external tracheal aperture in a terrestrial arthropod
"The entomologist carefully examined the beetle's spiracles to locate the distinct stigma on its thoracic segment."
a skin lesion that is a diagnostic sign of some disease
"The dermatologist confirmed the patient's diagnosis after identifying the raised, scaly stigma on their forearm as a classic symptom of psoriasis."
A mark of infamy or disgrace.
"The paleographer struggled to decipher the ancient manuscript because the rare ligature known as stigma had been mistaken for a standard abbreviation."
A ligature of the Greek letters sigma and tau, (Ϛ/ϛ).