is there a term for words whose abbreviation stole some of the previous word?

Ok that title isn't super clear, but my examples will be. Most common in compound/porte-manteaux words.
Helicopter (helico-pter) = copter
Labradoodle (labrador + poodle) = doodle.

There are more, I'm sure. Please tell me all the ones you can think of as well as what these darn things are called!!