Idiom definition : an expression that does not mean the same as the individual words: The words ``to hit the roof" say ``to hit against the top of a house", but the idiom actually means ``to become very angry. 

(source: Newbury House Online Dictionary, www.heinle.com/default.html) 

Here is a list of common idioms

A

Ask out (to ask someone on a date)

B

Bring about, bring on (cause something to happen)

Bring up (mention or introduce a topic)

C

Call back (return a telephone call)

Call in (ask to come in for a reason)

Call off (cancel)

Call on (ask to speak, or visit)

Call up (call on the telephone)

Catch up (reach the same position)

Check in (register at a hotel)

Check out (leave a hotel, or look at)

Check into (investigate)

Cheer up (make someone happier)

Clean up (make clean)

Come across (meet by chance)

Come back (to return from a defeat or injury)

Cross out (draw a line through)

Cut out (stop annoying activity)

D

Do over (do again)

Drop by, drop in (visit informally)

Drop off (leave something)

Drop out (quit (school))

F

Figure out (find the answer)

Fill out (complete a questionnaire)

Find out (discover information)

G

Get along [with] (relate well to someone)

Get back [from] (return from a place)

Get in, get into (enter a car, or arrive)

Get off (to exit a transportation)

Get on (to enter a transportation)

Get out of (avoid something)

Get over (to recover from illness)

Get through (finish)

Get up (arise from bed, or a chair)

Give back (return an item)

Give up (stop trying)

Go over (review or verify)

Grow up (become more mature)

H

Hand in (submit)

Hang up (conclude a telephone conversation)

Have on (be wearing something)

K

Keep out [of] (not enter)

Keep up [with] (stay at the same position)

Kick out (for to leave, to dismiss or eject forcefully or summarily) *Websters

L

Look after (take care of)

Look into (investigate)

Look out [for] (be careful)

Look over (review or check carefully)

Look up (look for information)

M

Make up (invent)

N

Name after (give a baby the name of someone else)

P

Pass away (die)

Pass out (to lose consciousness)

Pick out (select)

Pick up (go to get someone [car or other vehicule])

Point out (call attention to)

Put away (remove to a proper place)

Put back (return to original place)

Put off (postpone)

Put on (put clothes on one’s body)

Put up with (tolerate)

Put out (extinguish)

R

Run into, run across (to meet by chance)

Run out [of]  (finish a supply of something)

S

Show up (appear, come)

Shut off (stop a machine, light, tap)

T

Take after (resemble)

Take off (remove clothing, leave on a trip)

Take out (take someone on a date, remove)

Take over (take control)

Take up (begin a new activity)

Tear down (to demolish)

Tear up (to tear into pieces)

Think over (to consider carefully)

Throw away, throw out (discard, get rid of)

Throw up (vomit)

Try on (put on clothing to see if it fits)

Turn down (decrease volume or intensity)

Turn in (submit an assignment)

Turn off (stop a machine, light, tap)

Turn on (begin a machine, light, tap)

Turn up (increase in volume or intensity)