think, n.
2. a. What one thinks about something; an opinion.

1835 LADY GRANVILLE Lett. (1894) II. 187 My own private think is that he will execute another voluntary. 1861 J. BROWN Horæ Subs. Ser. II. 355 The cobbler..dispenses his ‘think’..to all comers on all subjects.



b. to have another think coming: to be greatly mistaken.

1937 Amer. Speech XII. 317/1 Several different statements used for the same ideathat of some one's making a mistake...[e.g.] you have another think coming. 1942 T. BAILEY Pink Camellia xxvii. 199 If you think you can get me out of Gaywood, you have another think coming. 1979 Jrnl. R. Soc. Arts CXXVII. 221/2 Any design consultant who thinks he is going to get British Leyland right by himself on his own has got another think coming.
[OED2]