nocturnal
noc.tur.nal \na:k-'t*rn-*l\ \-*l-e-\ aj [MF or LL; MF fr. LL nocturnalis,
fr. L nocturnus of night, nocturn]al, fr. noct-, nox night 1: of, relating
to, or occurring in the night {a ~ journey} 2: active at night {a ~
predator} - noc.tur.nal.ly av
Webster's English Dictionary