Alternative form of No.

Used on signs to indicate that entry into the area where the sign is displayed is forbidden.

(of airspace) In which aircraft are forbidden to fly. / (of people) Who are forbidden to board an aircraft.

Not functioning properly. / Of a place, not to be entered.

Alternative form of no go

An airspace in which aircraft, especially military aircraft, are forbidden to fly.

(cricket) The result of a one-day match in which a side fails to complete their innings, or to bat the minimum number of overs, because of bad weather.

(baseball) A game in which no batter on one of the teams got a hit.

(cricket) A ball delivered by a bowler in violation of any of the various laws; the extra run then credited to the batting side; the signal, with an arm outstretched, then made by the umpire.

(cricket, of a bowler) To bowl a no ball. / (cricket, of an umpire) To call and signal a no ball.