, v.aux. (usu. foll. by to + infin.; present and past indicated by the following infin.) 1 expressing duty or rightness (we ought to love our neighbours).
2 expressing shortcoming (it ought to have been done long ago).
3 expressing advisability or prudence (you ought to go for your own good).
4 expressing esp. strong probability (he ought to be there by now).
ought not the negative form of ought (he ought not to have stolen it).