Goold Brown,
The Grammar of English Grammars
“ II. An irregular verb is a verb that does not form the preterit and the perfect participle by assuming d or ed; as, see, saw, seeing, seen.III. A redundant verb is a verb that forms the preterit or the perfect participle in two or more ways, and so as to be both regular and irregular; as, thrive, thrived or throve, thriving, thrived or thriven.IV. A defective verb is a verb that forms no participles, and is used in but few of the moods and tenses; as, beware, ought, quoth. ”
