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Prefix · quantity / insufficiency

under-

Signals insufficiency or less than the required level: underestimate, underpaid, undercooked.

Basic

Written by Bryan López, English teacher · Updated

What does under- mean in English?

Under- is the direct opposite of over-. It almost always shows that something is below the necessary, correct or expected level. With verbs, it shows doing something insufficiently. With participles, it describes a state of insufficiency: something underpaid, undercooked or underdeveloped.

Under- also means "below"

Like over-, under- has a sense of place: below. And that sense is often carried over figuratively. A good example is undermine, which literally is to dig underneath something, and means to weaken. If you see under- next to a verb, ask yourself whether it is about "too little" or about "below".

How it is used

Attaches directly to verbs, past participles, and nouns:

  • under- + verb (insufficiency)
    estimate → underestimateperform → underperformcharge → undercharge
  • under- + past participle (state)
    paid → underpaidcooked → undercookeddeveloped → underdeveloped
  • under- + noun (position)
    ground → undergroundwater → underwaterline → underline

No spelling change to the root. Stress falls on the first syllable: /ˈʌndər/.

How it is pronounced

under-/ˈʌndər/

Tap the button to hear how the prefix sounds. Each word in the table has its own audio.

Examples

  • estimateunderestimateNever underestimate how long a project really takes.
  • paidunderpaidMany skilled workers in that sector feel underpaid.
  • cookedundercookedThey sent the chicken back because it was undercooked.
  • groundundergroundThey took the underground train to the airport.
  • performunderperformThe new model underperformed in almost every test.
  • lineunderlineThe teacher asked students to underline the key verbs.
  • mineundermineThe scandal began to undermine trust in the company.

Common mistakes

underestimate applies to numbers only
underestimate works for people, skills, and difficulty too

"Don't underestimate her" = do not think her less capable than she is. The prefix applies to any kind of assessment, not just numerical ones.

underline = only physically drawing a line
underline also means to emphasise or highlight

"This underlines the need for change" = this highlights the need for change. The figurative use is extremely common in formal writing.

A trick to remember it

Picture something that does not reach the level it should. Underpaid = the salary does not reach the right level; undercooked = the cooking does not reach the right level; underperform = the results do not reach the expected level. That single image of "falling short" applies to every under- word.

Practise what you learned

Exercise 1 · Form the word

Never ___ how long a creative project takes from start to final delivery.

Hint: under- + estimate = ?

Exercise 2 · Pick the right one

"Many talented employees feel ___ despite years of experience and strong results."

Exercise 3 · Pick the right one

What is the difference between "underground" and "underwater"?

Frequently asked questions

What does the prefix under- mean in English?

The prefix under- signals insufficiency or less than the required level: underestimate, underpaid, undercooked.

How do you pronounce under-?

The prefix under- is pronounced /ˈʌndər/. For example, "underestimate".

Can you give an example of a word with under-?

"estimate" becomes "underestimate". It is a typical example of the under- prefix.

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