Lay into (2) INFORMAL
If you lay into someone, you criticize them in an angry way.
Lay off
If you lay someone off, you stop employing them and tell them they no longer have a job.
lay out (1)
If you lay things out, you spread them out so they're easy to see or easy to use.
lay out (2)
to explain an idea or a plan clearly and in detail
Laze around
to relax and do very little
Lead to
to cause something to happen
Lead up to
If a period of time or a series of events leads up to a particular event, it happens just before it.
Leave behind
If you left something behind, you forgot to bring it with you.
Leave in
If you leave something in, you don't take it out or cut it out.
Leave out
If you leave something out, you don't include it or count it.
Leave to
to give someone responsibility for dealing with something or making a decision about something
Leave up to
If you leave something up to someone, you let them do it or you give them responsibility for it.
let down (1)
If you let someone down, you disappoint them by not doing what they expect you to do.
let down (2) 
to release the air from something like a tyre or a blow-up mattress
Let go of
to stop holding something or someone
Let in
If you let someone in, you allow them to enter a room or a building.
let off (1)
to give someone little or no punishment for doing something wrong
let off (2)
to make something explode
let out (1)
to allow somebody or something to leave a place
let out (2)
to make a particular sound or noise
let out (3)
to rent a room or a building to somebody
Let up
to become weaker or to become less intense