Senses
下降 to decrease
To go down in degree, quality, or quantity; to decline.
下降 to descend
To go or come down from a higher place; to drop or fall.
下降 to marry a commoner
(literary) Used to describe a princess marrying someone of a lower social rank.
下降 to arrive
(honorific, archaic) To deign to visit; to arrive, used when referring to a guest of higher status.