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. In English Hints we're talking about words that are 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, whereas hyperactive or overactive both mean more active than normal. Interactive describes action between people or ways people can interact with computers besides just reading the screen.

The lists below give examples of the word family 'act' (showing the part of speech of each family member) and then of 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'

Whitewater rafting with text: “Act!” Have an action plan. Don’t drift through life reacting to problems, but press forward, actively seeking solutions and interacting with others to find them.Did you notice in the picture caption how “act” changes meaning and position with different prefixes and suffixes?
Whitewater rafting, with text: “Act!” Have an action plan. Don’t drift through life reacting to problems, but press forward, actively seeking solutions and interacting with others to find them.Did you notice in the picture caption how “act” changes meaning and position with different prefixes and suffixes?

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, after applying for and receiving 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 “getting out and doing something” rather than just passively letting things 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? Participate actively in finding solutions to problems, but 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.


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 person or thing that receives the action, as in transactions or action (in paragraph 3.) Sometimes there can be several nouns in the same word family, especially if one is a concept (like activity) and one is a person (like actor or actress.)

Notice that the infinitive (the ‘to’ form) of a verb can be the subject of a sentence, acting as a noun as in to act and to activate (the first use.)

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 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. Adjectives can also be made (less commonly) 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: 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, and the past participle (usually ending in -ed) to express 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 really 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 is an adverb. It tells you how to participate. (Another example: My brother always works proactively, He thinks ahead and takes steps to avoid problems.)

Related Pages and Practice with Word Families

For more information, see English Parts of Speech and Negative Prefix List. Also see List of Suffixes if you want to know more about how different suffixes can change a word’s part of speech, taking a verb and making it a noun (or vice versa), making an adjective into an adverb, etc,

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

HomeLearn English Vocabulary>Word Families.

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