Word Families: Boost Your Vocabulary 

Recognizing word families can multiply your word power! So what are they? “Word families” can mean several types of word groups. Here we're talking about words made from the same root by adding different suffixes or negative prefixes. 

Adding other prefixes to roots makes bigger changes in meaning. The words are still related, but not quite as closely. For example, to counteract means to act against something, and to react is to act in response to something.  

The adjective 'inactive' means not active. 'Hyperactive' or 'overactive' both mean more active than normal. 'Interactive' describes action between people. It's also used for ways people can interact with computers beyond reading the screen. 

The lists below give examples of the word family 'act' (showing the part of speech of each family member.) Then it explains related families made by adding a prefix to 'act,' showing only their most common words. (Parts of speech are the same as for words of the same suffix in the first list.)

The Word Family 'Act'

Photo of people paddling a raft, with a caption: 'Act! Have an action plan. Don't drift through life reacting... but press forward actively...'-- plus a discussion of the forms of 'act.'

Verbs-    Nouns-   Adjs (or Advs)

act-          act, actor  --

--             action -  actionable

--              --            active, actively 

activate- activation -activated

--             activity   --

--             activism, activist   --

--             inaction-  inactive

--              inactivity --

Related families
(from the same root as 'Act')

  • counteract, counteractive
  • deactivate, deactivation
  • enact

  • hyperactive, hyperactivity
  • interact, interaction, interactive, interactively, interactivity
  • overactive
  • overreact, over-reaction
  • proactive, proactively
  • react, reaction, reactivate, reactivation, reactive, reactivity
  • transact, transaction

Definitions and Examples

To act is to do something. We say, “Actions speak louder than words.”

To activate is to make something (like an account) active. For example, when you receive a credit card, you must call a certain phone number to activate it before you can use it. The call confirms that you received the card in the mail. Once it is activated you can use it for transactions (in this case purchases).

An active person does things. Activity means doing something, not waiting for things to happen. (Hyperactivity or being overactive is moving around or doing too much.)

It is wise to be proactive, and take action before problems get serious. The opposite approach is waiting to react to problems. However, there can also be a problem if a person acts before he thinks!

So what’s the best advice?  Actively look for solutions to problemsbut be sure to think first!

newspaper with a drama review using many forms of the word 'act.'What an act! (How many forms of ‘act’ can you find?)

Parts of Speech in Sentences

The definitions above show how to use the different parts of speech in the 'act' family in sentences. Here's a little more explanation.

NOUNS tell who or what the sentence is about (as the subject of the sentence.) See actions, activity, & hyperactivity in the definitions above.

Nouns can also be the object of a verb or preposition. The 'object' is the person or thing that receives the action. 

There can be several nouns in the same word family. For example, activity is a concept and an actor or actress is a person.

Notice that the infinitive (the ‘to’ form) of a verb can be the subject of a sentence. It acts as a noun. (See the first use of to activate above.)

Sometimes the present participle of a verb can also act as a noun. (It’s called a gerund when it is used as a noun.) 'Acting’ is a gerund in the following sentence. “Acting is a profession that requires constant practice.”

VERBS usually show the action of a sentence: what a noun does. To activate, to react, & acts (in paragraph 3) are verbs.

ADJECTIVES describe (tell about) nouns. Acting, activated, active, overactive, & proactive are adjectives. (Acting can also be a noun or the present participle of a verb.) Activated, like many adjectives, is made using the past participle of a verb.

We sometimes form adjectives from the present participles of verbs. “Mr. Miller is the acting vice president of the company until Mr. Baker returns.”

Sometimes there are two or more adjectives made from the same verb. Examples: boring and bored, frightening and frightened, surprising and surprised.

In these cases we use the present participle (-ing form) to express the cause of a feeling. The past participle (usually ending in -ed) expresses the result or the feeling itself.

Examples: “Mr. Smith’s class last night was very boring!

We were so bored we counted the minutes until ten o’clock!"

“Have you ever had a frightening experience? Some people get so frightened at horror movies that they scream.”

ADVERBS modify verbs, adjectives, or other adverbs. They describe how something is done. Actively and proactively are adverbs. ("My brother always works proactively, He thinks ahead and takes steps to avoid problems.")

Related Pages & Practice

Picture of earth & explanation of negative prefixes (un-, in-, mis-, etc.) All reverse root meanings, but they aren't the same. Uninformed: Is the world flat? Misinformed: My Dad says it is.'

The explanations & examples in this negative prefix list can help you use them without confusion. 

Puzzle pieces linked together to show 'active,' 'activate,' & 'activation.'
Text: 'Suffixes can turn a verb like act into an adjective, noun, or another verb (above) or show tense or number.'

Use this list of suffixes (with examples) to build your vocabulary. 

3 fish swimming in one direction & a different-colored fish swimming in the opposite direction. One fish says 'He always was a nonconformist.'

Knowing a few roots & prefixes can help you figure out meanings of new words. 

For more information than is on the pages above, check out  English Parts of Speech

To practice with word families, see Word Family Practice and Word Formation Examples & Exercises.

HomeLearn English Vocabulary>Word Families.

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