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TOEIC Link Part 5: defective versus deficient

Defective and deficient share the de- prefix and a sense of "something wrong," but they fail in different directions: defective means having a fault or flaw so it does not work properly, while deficient means lacking enough of something. Part 5 tests whether the blank means faulty or in short supply.

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TOEIC Link Part 5: defective versus deficient

Defective and deficient both start with de- and both signal that something is wrong, which is why Part 5 likes to swap one for the other. But they describe two different problems. Defective means having a fault or flaw, so an item does not work as it should. Deficient means lacking enough of something, so a quantity or standard falls short. One is about a broken thing; the other is about a missing amount. For the wider set of look-alike traps, start with the commonly confused word pairs master index.

The core rule: faulty versus in short supply

  • defective = having a fault or flaw; not working properly (adjective). The factory recalled every defective unit. / Customers may return any defective merchandise for a full refund. It answers what is wrong with this item? Link defective to faulty and broken: the object exists but has a defect.
  • deficient = not having enough of something; below a required level (adjective). The audit found the internal controls to be deficient. / A diet deficient in iron can cause fatigue. It answers what is this short of? Link deficient to lacking and inadequate: something needed is missing or insufficient.

The endings echo the meanings. Defect-ive is built on the noun defect (a flaw), so it describes a thing that has a flaw. Defici-ent is built on deficit (a shortfall), so it describes a thing that falls short of a required amount. If the blank means the product is broken, choose defective; if it means a supply or standard is not enough, choose deficient.

How Part 5 sets the trap

Part 5 puts both words near a noun that could plausibly be faulty or in short supply, forcing you to read what the sentence actually claims.

The inspector rejected the shipment because several components were __.

If the components are broken, the answer is defective. If the sentence instead said the shipment was __ in essential components, the answer would be deficient — the shipment lacks the right quantity. Notice the grammar clue: deficient often pairs with in (deficient in X), while defective stands alone before or after the noun (a defective part / the part is defective).

Business collocations to memorize

  • defective: a defective product, defective merchandise, a defective part, a manufacturing defect, replace the defective unit
  • deficient: deficient in vitamins, a deficient control system, nutritionally deficient, deficient documentation, remedy the deficiency

When TOEIC talks about returns, recalls, and warranties, the trigger word is usually defective. When it talks about audits, nutrition, standards, or requirements not being met, the trigger is usually deficient.

Quick self-check

  1. The warehouse returned the __ scanners to the supplier. → defective (they do not work)
  2. The report was __ in supporting data. → deficient (it lacks enough data)
  3. Any __ appliance is covered under the one-year guarantee. → defective (faulty item)
  4. Their training program was found __ in several key areas. → deficient (falls short of the standard)

If the item is broken, it is defective; if the amount or standard is not enough, it is deficient.

Related confusable pairs