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).
[ OE ahte, past of agan OWE ]