Xem thêm: unanticipated, unforeseen, unlooked-for, out of the blue(p), unexpectedly
adj.
unanticipated and disconcerting lines of development"- H.W.Glidden; "unforeseen circumstances
a virtue unlooked-for in people so full of energy
like a bolt out of the blue
adv.
her brother showed up at the wedding out of the blue