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Word Study · Prefixes
Prefixes over-, under- and sub-: Too Much, Not Enough, Below
Learn what over-, under- and sub- add to a base word, build and spell new words like overcook, underpay and subway, and check tricky words like understand.
The idea
Prefixes over-, under- and sub- all point to a position or an amount. Like other prefixes, they are added to the beginning of a base word and the base word keeps its spelling. Cook becomes overcook, undercook; way becomes subway.
over- usually means too much (overcook means cook for too long; oversleep means sleep too long) or above (overhead means above your head). under- usually means not enough (underpay means pay too little) or below (underground means below the ground). sub- means below or a smaller part (submarine goes below the water; a subheading is a smaller heading under a main heading).
Notice that over- and under- can be opposites: overcook and undercook, overpay and underpay. That makes them easy to learn together. sub- is a cousin of under-, and it appears more often in science words and in school work (subtitle, subtopic).
Use the cover test. Cover the prefix and check that a real base word is left and that the meaning fits. Overflow is over + flow, so it means flow over the edge. Understand looks like under + stand, but it does not mean stand below something, so you learn it as a whole word. Remember that no letters are dropped when you join the pieces: underline keeps every letter of under and every letter of line.
Word bank
overcook
verb · oh-ver-KOOKto cook for too long
Example: If you overcook pasta, it gets mushy.
overflow
verb · oh-ver-FLOHto run over the edge of a container
Example: The bathtub began to overflow.
overdue
adjective · oh-ver-DYOOlate; past the time something was supposed to be done or returned
Example: My library book is two days overdue.
overgrown
adjective · oh-ver-GROHNgrown too large, or covered with plants
Example: The path was overgrown with weeds.
oversleep
verb · oh-ver-SLEEPto sleep longer than you meant to
Example: I overslept and missed the bus.
underline
verb · un-der-LYNto draw a line under a word or sentence
Example: Underline the topic sentence in red.
underground
adjective · un-der-GROWNDbelow the surface of the earth
Example: Moles live in underground tunnels.
underwater
adjective · un-der-WAH-terbelow the surface of the water
Example: The underwater photos showed a coral reef.
underpay
verb · un-der-PAYto pay someone too little
Example: It is unfair to underpay workers.
undercook
verb · un-der-KOOKto cook for too short a time
Example: Undercooked chicken is not safe to eat.
subway
noun · SUB-waya train that runs on tracks below the ground in a city
Example: We took the subway to the museum.
submarine
noun · SUB-muh-reena ship that can travel under the water
Example: The submarine dived deep into the ocean.
subtitle
noun · SUB-ty-tulwords at the bottom of a screen that show what people say; or a second title
Example: I watched the movie with French subtitles.
subheading
noun · SUB-hed-inga small heading under a main heading
Example: Each subheading tells what the next part is about.
subtopic
noun · SUB-top-ika smaller topic that is part of a larger topic
Example: Habitats is one subtopic of our animal unit.
Worked examples
Example 1 · Work out a new word
What does overprotect mean?
- Find the prefix: over-, meaning too much.
- Look at the rest: protect, meaning keep safe.
- Put them together: protect too much.
Overprotect means to protect someone more than is needed.
Example 2 · Choose over- or under-
A cake was baked for 10 minutes when the recipe said 30. Which word fits: overbaked or underbaked?
- Compare the time: 10 is less than 30, so there was not enough baking.
- Not enough is the meaning of under-.
- Check the spelling: under + baked, with no letters dropped.
underbaked
Example 3 · Is the meaning still there?
Does understand mean stand under something?
- Cover under. What is left is stand, a real word.
- But understand means to get the meaning of something, not to stand below it.
- The meaning test fails, so learn understand as a whole word.
No. Understand looks like it has under-, but the meaning does not come from its parts.
Example 4 · Spell it by parts
Add sub- to topic and then add sub- to heading. How many letters change in each base word?
- sub + topic = subtopic. Write the whole base word after the prefix.
- sub + heading = subheading.
- Do not add or drop letters when joining.
subtopic and subheading. No letters in the base words change.
Common mistakes
Why this fails: over- means too much and under- means not enough. Ask whether the amount was more or less than it should be.
Why this fails: The base word keeps all its letters. Under + line is underline, and sub + title is subtitle.
Why this fails: Say the sounds slowly: o-ver and un-der each have two syllables with a vowel in each part. The prefix is spelled over and under.
Why this fails: Understand, overt and subject do not mean what the parts suggest. Use the cover test and check the meaning.
Why this fails: These words are one word with no space or hyphen. When in doubt, check a dictionary.
Foundation
Foundation practice
Learn what each prefix means.
1. What does under- usually mean in underpay and undercook?
- Too much
- Not enough
- Again
- Before
2. What does over- mean in oversleep?
- Sleep too little
- Sleep again
- Sleep too long
- Sleep below
3. Which word means a ship that goes under the water?
- overmarine
- submarine
- remarine
- premarine
4. Which word fits? "The library book is three days ___."
- underdue
- subdue
- overdue
- redue
5. Which is the correct spelling of the word that means draw a line below?
- undaline
- underline
- undline
- underlyne
Practice
Practice practice
Choose the right prefix and spelling.
6. A recipe says to bake for 40 minutes. Maya bakes it for 20. Which word describes the cake?
- overbaked
- underbaked
- rebaked
- subbaked
7. The bathtub is full and water spills onto the floor. Which word fits?
- underflow
- subflow
- reflow
- overflow
8. Three of these words use a prefix that means below. Which one does not?
- underground
- underwater
- submarine
- oversleep
9. Which sentence uses the word correctly?
- The soup tastes better if you overcook it for one second.
- I used a subheading to name the next part of my report.
- We took the undertrain to the museum.
- The workers were overpaid, so they got too little.
10. Which word completes the sentence? "The grass was ___ because nobody had cut it all summer."
- undergrown
- subgrown
- regrown
- overgrown
Challenge
Challenge practice
Check tricky words and mixed lists.
11. Which word uses over- to mean too much, so that the parts help you work out the meaning?
- overlook
- overall
- overeat
- overture
12. Which statement about understand is correct?
- It means stand below something.
- It is spelled with a hyphen: under-stand.
- It starts with under, but the meaning is not stand under.
- It means not enough standing.
13. Which list has only words that mean too much or too long?
- overcook, oversleep, overgrown
- overcook, undercook, overflow
- oversleep, underline, subway
- overdue, underpay, subtitle
14. One word is spelled wrong. Which one?
- subtitle
- subway
- underwater
- unnderground
15. Choose two words from the word bank, one with over- and one with under- or sub-. Use each in a sentence of your own and underline the prefix.
Answer key
- 1. Not enough
Underpay means pay too little, and undercook means cook for too short a time. Too much is the meaning of over-. Again belongs to re-, and before belongs to pre-. - 2. Sleep too long
Over- here means too much, so oversleep is to sleep longer than planned. Sleeping too little would use under-, again would use re-, and below would use under- or sub-. - 3. submarine
Sub- means below, and marine means of the sea. The other choices are not English words. - 4. overdue
Overdue means late, past the day it was due. Underdue and redue are not English words, and subdue is a real word that means to calm or bring under control, not late. - 5. underline
Under + line keeps both parts whole. The other choices drop letters or change the vowel in line. - 6. underbaked
Twenty minutes is less than forty, so it was baked not enough. Overbaked means too long, rebaked means baked again, and subbaked is not a word. - 7. overflow
Overflow means to run over the edge. Underflow, subflow and reflow do not describe water spilling out of a tub. - 8. oversleep
Underground, underwater and submarine all mean below something. Oversleep uses over- to mean too long. - 9. I used a subheading to name the next part of my report.
A subheading is a smaller heading under a main one. Overcooking for one second would not make soup better, the city train is a subway, not an underway, and overpaid means paid too much, not too little. - 10. overgrown
Overgrown means grown too long or thick. Regrown means grown again, and undergrown and subgrown do not fit the meaning. - 11. overeat
Overeat means eat too much: over- plus the real word eat. Overlook (to miss or ignore) and overall (in total) do not mean what their parts suggest, and overture (an opening piece of music) has no base word ture. - 12. It starts with under, but the meaning is not stand under.
Understand means to get the meaning of something. The letters under are in the word, but the meaning does not come from under- plus stand. It is also written without a hyphen. - 13. overcook, oversleep, overgrown
Each of those has over- meaning too much or too long. The other lists add undercook (not enough), underline, subway, underpay and subtitle, which do not mean too much. - 14. unnderground
Under + ground has only one n in the middle: underground. The other three words are spelled correctly. - 15. Sample answer: I overslept this morning, so I ran to the bus stop. We rode the subway to the aquarium.
Answers can vary. Check that each sentence uses the word with its correct meaning, that the spelling matches the word bank, and that the prefix really adds the meaning of too much, not enough or below.