strong verb
Definition - A verb that does not form its past participle by adding a suffix that ends in d, -d, or t.

1. As opposed to weak verbs, which do form past participles by adding these suffixes.
2. Weak verbs have just four forms (e.g. start, starts, starting, and started), whereas strong verbs have five forms (e.g. begin, begins, beginning, began, and begun).
3. The copula to be is a special case: it has eight forms: be, am, is, are, being, was, were, and been (as well as — archaically — art, wast, and wert).

Example -

(1) sing, sang, sung
(2) break, broke, broken

Etymology -
The terms strong verb and weak verb are loan translations of, respectively, the German starkes Verb and schwaches Verb. Both terms were coined by the linguist Jacob Grimm.

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