The Principal Parts of Verbs

principal parts of a verb
The principal parts of the verb see. Some grammarians regard the present participle (in this case seeing) as a distinct part; others don't. (mrPliskin/Getty Images)

In English grammar, the term "principal parts" describes the basic forms of a verb including the base or infinite, the past tense or preterite and the past participle.

From the base form, one can derive the third-person singular "-s" form in words like "looks" and "sees" and the present participle "-ing" in words like "looking" and "seeing," with some textbooks regarding the present participle as a fourth principal part of a verb.

Irregular verbs may have three, four, or five forms, though, depending on whether or not a form is used for two or three form types. For all except the verb be, which may be unpredictable, the "s-" and "-ing" participle are always available and its alteration of the base acts predictably.

Understanding Principal Parts of Regular and Irregular Verbs

In order for new English learners to best understand how not to make mistake when conjugating irregular verbs, one must first grasp the concept of the principal parts of regular verbs. In most cases, verbs will change uniformly when "-ed," "-s," and "-ing" are added, keeping their original form spelling but changing the tense of the verb.

However, irregular verbs, which defy the usual pattern, often change spelling entirely depending on tense, especially in the case of forms of the verb be. Roy Peter Clark uses the examples of lie and lay and run in "The Glamour of Grammar: A Guide to the Magic and Mystery of Practical English." For run, Clark states, "the simple past, we know, is not runned...the principal parts are run, ran, run." In this case, the irregular verb has its own rules.

If you are confused about the correct principal part of a verb, it's best to consult a dictionary. In the case of regular verbs, only one form will be given, but irregular verbs will give the second and third parts after the verb such as it does for the words "go," "went," and "gone."

Primary and Perfect Tenses

The principal parts of verbs effectively carry a sense of time with their use, but the manner in which they convey the action of the verb determines which tense classification linguists and grammarians categorize them as either primary or perfect in either the present, past, or future tenses.

In the primary tenses, an action is considered ongoing, even if it occurred in the past or future tense. Take the verb "call" as an example. For the present tense, one would say "today, I call," while in the past primary tense, one would say "I called" and in future would say "I will call."

On the other hand, perfect tenses describe actions that have already been completed. As Patricia Osborn puts it in "How Grammar Works: A Self-Teaching Guide," verbs in this tense are called perfect because "anything perfect is complete, and the perfect tenses stress an action at its completion." In the example of call, one would say "Before now, I have called," for present perfect, "I had called" for past perfect and "I will have called" in the future perfect tense. 

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Nordquist, Richard. "The Principal Parts of Verbs." ThoughtCo, Apr. 5, 2023, Nordquist, Richard. (2023, April 5). The Principal Parts of Verbs. Retrieved from Nordquist, Richard. "The Principal Parts of Verbs." ThoughtCo. (accessed May 31, 2023).