Bethink

The verb 'to bethink' is an archaic usage. You are advised not to use it in modern academic English. It is not a more elegant way of saying 'to think'. Its usage was usually as a reflexive verb, 'to bethink oneself of [something]', and its basic meaning was 'to remember' or 'to bring to mind'. It was sometimes used to mean 'to take it into one's head to...', or 'to propose an idea to oneself'. Other meanings existed, but they are all listed as obsolete in OED. The past tense and past participle are both bethought. (For a further etymological note about the origins of this word, see be-.

Fowler (1931) lists the use of bethink as if it meant 'think' as an example of his first class of malaprops.