Forget

'To forget' is an irregular verb. Its forms are given here:

Base form	past tense	-ed participle	Remarks
forget	forgot	forgotten	In American English, the -ed participle too can be forgot See also get (irregular verb), in class 6 F.

This is one of the "the 250 or so irregular verbs" listed in Quirk 1985. The list "contains most of the irregular verbs in present-day English ... but is not meant to be exhaustive, particularly with regard to derivative verbs." AWE has copied most of the entries in that list. The verb 'to forget' belongs to Quirk's Class 4 A c.

'To forget' is derived from Get (irregular verb), but has retained the older form of the past participle which 'to get' has lost in British English - although American English still retains it for some meanings. Cf. beget.

You may want to see a comment on the origin of forget at for- - fore-.