An irreplaceable verb "lassen"

The meaning of German verbs varies depending on the prefix or the preposition they are used with. But there are some tricky verbs that have different meanings even without any changes in their form. 

One of the best examples is the verb "lassen". It is a very useful irregular (strong) verb with the basic meaning of "to allow" or "to let." But it has many other meanings and is used often in everyday German. 

Principal Parts: lassen, ließ, gelassen

1. lassen (erlauben, zulassen)

English Meaning: to allow, let

Examples: Sie lässt ihren Hund auf dem Bett schlafen. (She lets her dog sleep on the bed.) Das lasse ich mit mir nicht machen. (I won't stand for / put up with that. Lit., "I won't allow that with me.")

2. lassen (veranlassen, helping verb, modal verb)

English Meaning: to get / have done

Examples: Sie lassen sich scheiden. (They're getting a divorce.) Er hat sich die Haare schneiden lassen. (He got a haircut.) Lassen Sie Herrn Schmidt hereinkommen. (Please send Mr. Schmidt in.)

3. lassen (vorschlagen)

English Meaning: to let (let me, let's)

Examples: Lass uns gehen. (Let's go.) Lass ihn das machen. (Have / Let him do that.)

4. lassen (aufhören, unterlassen)

English Meaning: to stop, refrain from (doing something)

Examples: Lassen Sie das! (Stop doing that! Leave that alone!) Er konnte es einfach nicht lassen. (He just couldn't resist it.) Sie kann das Rauchen nicht lassen. (She can't quit / give up smoking.)

5. lassen (stehen lassen, zurücklassen)

English Meaning: to leave (sth somewhere)

Examples: Bitte lass den Koffer stehen. (Please leave the suitcase [standing] where it is.) Lassen Sie sie nicht draußen warten. (Don't leave them waiting outside.)

6. lassen (übriglassen)

English Meaning: to leave (behind, over)

Example: Die Diebe haben ihnen nichts gelassen. (The thieves cleaned them out / left them with nothing.)

7. lassen (nicht stören)

English Meaning: to leave alone, leave in peace

Example: Lass mich in Ruhe! (Leave me alone!)

8. lassen (bewegen)

English Meaning: to put, place, run (water)

Examples: Hast du ihm Wasser in die Wanne gelassen? (Did you run his bath water?) Wir lassen das Boot zu Wasser. (We're putting out the boat / putting the boat into the water.)

9. lassen (zugestehen)

English Meaning: to grant, admit

Example: Das muss ich dir lassen. (I'll have to grant you that.)

10. lassen (verlieren)

English Meaning: to lose

Example: Er hat sein Leben dafür gelassen. (He laid down his life for that.)

11. lassen (möglich sein, reflexive)

English Meaning: to be possible

Examples: Hier lässt sich gut leben. (One can live well here.) Das Fenster lässt sich nicht öffnen. (The window won't open. The window can't be opened.) Das lässt sich nicht leicht beweisen. (That won't be easy to prove.)

12. lassen (verursachen)

English Meaning: to cause, make (sb do sth)

Example: Die Explosion ließ ihn hochfahren. (The explosion made him jump.)

Another posts to this verb: 

Idioms and Expressions with "lassen"

Compound verbs based on "lassen"

http://german.about.com/od/vocabulary/a/lassen.html