i Register
In some senses, ill-advised is marked as informal. Watch for register when choosing this word.
adj
Carried out without the benefit of wise counsel or careful deliberation, or carried out with unwise counsel.
Ashley Young's ill-advised attempt to dribble out of danger ended in a corner and when Steven Gerrard's delivery was headed goalwards by Daniel Agger, Sturridge deflected it home from virtually on the line.
Acting unwisely.
You are ill-advised to boast of that foul deed.