From WordNet (r) 3.0 (2006) [wn]:
nightly
adv 1: at the end of each day; "she checks on her roses nightly"
[syn: nightly, every night]
adj 1: happening every night; "nightly television now goes on
until 3:00 or 4:00 a.m."
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Nightly \Night"ly\, a.
Of or pertaining to the night, or to every night; happening
or done by night, or every night; as, nightly shades; he kept
nightly vigils.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Nightly \Night"ly\, adv.
At night; every night.
[1913 Webster]