нары́вник

noun, masculine, animate, uncountable

very rarely used word (top 60,000)

1.
blister beetle, cantharides
Нарывники используются для получения лекарственных средств. - Blister beetles are used to obtain medicinal substances.
2.
a person suffering from boils, a person prone to abscesses
В старые времена нарывник обращался к знахарю за помощью. - In olden times, a person suffering from boils would turn to a healer for help.
3.
drawing plaster, poultice (for boils)
Наложили нарывник на больное место. - They applied a drawing plaster to the sore spot.

Declension