na-adjective, noun which may take the genitive case particle 'no', noun
Primarily a medical/technical term describing a dry condition or state, such as dry pleurisy. Often used attributively (乾性の) or as an adjectival noun (乾性な).
Dry pleurisy is a type of pleurisy where fluid does not accumulate.
This region has a dry climate with little rain throughout the year.
Compound of 乾 (kan, 'dry') and 性 (sei, 'nature' or 'property'), literally 'dry nature'. The exact historical derivation is uncertain, but it follows a common Sino-Japanese pattern for forming technical terms.