principal parts

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun plural In traditional grammars of inflected languages, the forms of the verb that are considered basic and from which all other forms of the verb are derived.
• noun plural In English, the present infinitive (play, eat, put), the past tense (played, ate, put), the present participle (playing, eating, putting), and the past participle (played, eaten, put).