Why is the ninth month called September?
c.1600, "insensitivity to pain," from French indolence (16c.), from Latin indolentia "freedom from pain, insensibility," noun of action from indolentem (nominative indolens) "insensitive to pain," used by Jerome to render Greek apelgekos in Ephesians; from Latin in- "not, opposite of, without" (see in- (1)) + dolentem (nominative dolens) "grieving," present participle of dolere "suffer pain." Sense of "laziness" (1710) is from notion of "avoiding trouble" (cf. taking pains).