✅ Mastering Word Families: Avoiding Parts of Speech Traps on TOEIC Part 5

Knowing a single word isn’t enough in Part 5 — you need to know its whole family.


If you can’t instantly switch between success, succeed, successful, and successfully, you’re walking straight into one of TOEIC’s most common traps.

💥 Why TOEIC Tests Word Families

Part 5 isn’t just testing vocabulary — it’s testing function.
The test checks whether you know how a word works in the sentence:

  • Noun vs verb

  • Adjective vs adverb

  • Same-looking words with different grammatical roles

It’s a quick way to see if you’re reading for structure, not just meaning.

🧪 Sample Question

The marketing team’s latest campaign was a huge ___ for the company.

A) succeed
B) success ✅
C) successful
D) successfully

Why B? The blank needs a noun (what the campaign was). Success is the noun; the others are different parts of speech.

🔄 Classic TOEIC Word Family Traps

  • effect (noun) vs affect (verb)

  • efficient (adjective) vs efficiency (noun)

  • applicant (noun) vs apply (verb) vs applicable (adjective)

  • decision (noun) vs decide (verb) vs decisive (adjective)

  • performance (noun) vs perform (verb) vs performer (noun)

These aren’t pure vocabulary tests — they’re grammar disguised as vocab.

🎯 How to Choose the Right Word Form

  1. Read the whole sentence, not just the blank.

  2. Ask: What part of speech is missing?

  • Describing a noun? → Adjective (effective)

  • Describing a verb? → Adverb (efficiently)

  • Doing the action? → Verb (apply)

  • Subject or object? → Noun (confidence)

⚠️ Common TOEIC Clues

  • Articles (a, the) → usually followed by a noun.

  • “To” + verb → base form of the verb.

  • “Be” + adjective → describes a state.

  • “Was done ___” → usually needs an adverb.

  • “One of the most ___” → superlative adjective.

Spot these, and you can often cut 2–3 wrong answers before thinking about meaning.

🧠 The Mindset Shift

When you see decision / decide / decisive / decisively, don’t ask “What do they mean?”
Ask “What job does this word need to do in the sentence?”
That single shift will boost both speed and accuracy.

Final Word

Word family questions are fast, frequent points once you’ve trained your eye for function. Learn nouns, verbs, adjectives, and adverbs together, and practise spotting what the sentence is asking for.

For more strategies and resources to master TOEIC grammar in context, visit the English Library Collection and start locking in word family accuracy today.

🔍 Hidden FAQ – Word Families & Parts of Speech (TOEIC) Q1: What is a word family in English grammar? A: A word family is a group of words that share the same root but have different forms, like “decide” (verb), “decision” (noun), “decisive” (adjective), and “decisively” (adverb). Q2: Why does TOEIC test word families so often? A: Because they reveal whether you understand how words function in a sentence, not just their meaning. It’s one of the fastest ways TOEIC checks your grammar skills. Q3: How do I know which form to use in a sentence? A: Look at the grammar around the blank. If it’s after an article (“a,” “the”), it’s likely a noun. If it follows “will” or “to,” it’s probably a verb. Clues are everywhere. Q4: What’s the difference between “effect” and “affect”? A: “Effect” is usually a noun (a result), while “affect” is a verb (to influence). TOEIC loves to test this pair because the words sound similar but have different roles. Q5: What part of speech is tested the most on TOEIC? A: TOEIC frequently tests adjective/adverb confusion — for example: “efficient” vs “efficiently.” If a word is modifying a verb, you usually need an adverb. Q6: Can’t I just choose the word that “sounds right”? A: That’s risky. TOEIC often makes all the answer choices sound natural. You need to understand sentence structure, not just rely on feeling. Q7: What’s a good way to study word families for TOEIC? A: Group them in sets. For example, for “apply,” study “applicant,” “application,” “applicable,” and “applied.” Then practise with example sentences. Q8: How do I know if I need a verb or a noun in the blank? A: Ask: “What is the subject doing?” If the blank is the action, it’s a verb. If the blank names a thing or idea, it’s a noun. Grammar clues are key.