Толковый словарь английского языка Oxford English Reference - ought

1. 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). Phrases and idioms ought not the negative form of ought (he ought not to have stolen it). Etymology: OE ahte, past of agan OWE 2. n. (also aught) colloq. a figure denoting nothing; nought. Etymology: perh. f. an ought for a NOUGHT; cf. ADDER 3. var. of AUGHT(1).