in Catholicism, "devotions consisting of special prayers or services on nine successive days," 1745, from Medieval Latin novena, fem. of Latin novenus "ninefold," from novem "nine" (see nine).
"Roman Catholicism" (usually, if not always, with a disparaging savor; in some contexts suggesting political allegiance to the Vatican), 1670s, from Roman + -ism. Other words in the same sense from about the same time were Romanish (Old English, but 1590s specifically of Catholics); Romanist (1520s); Romanistic.
c. 1400 as a term in astronomy, "angular distance of a star below the horizon," from Old French depression (14c.) and directly from Medieval Latin depressionem (nominative depressio), noun of action from past participle stem of Latin deprimere "to press down, depress" (see depress).
The literal sense "act of pressing down, state of being pressed down" is attested from 1650s. The meaning "dejection, state of sadness, a sinking of the spirits" is from early 15c. (as a clinical term in psychology, from 1905); meteorological sense is from 1881 (in reference to barometric pressure); meaning "a lowering or reduction in economic activity" was in use by 1826; given a specific application (with capital D-) by 1934 to the one that began worldwide in 1929. For "melancholy, depression" an Old English word was grevoushede.
A melancholy leading to desperation, and known to theologians under the name of 'acedia,' was not uncommon in monasteries, and most of the recorded instances of medieval suicides in Catholicism were by monks. [W.E.H. Lecky, "A History of European Morals," 1869]