I've heard this term used a few times to describe a really smooth landing (one where you hardly feel a bump). But where does this term actually come from? I'm not sure how grease (a lubricant) came to symbolize a low g-load on landing?
I've always heard this referred to as a "greased landing" or a "greaser", but never a "greaser landing".
My understanding is that it is referring to a landing that was so good that somebody must have greased the entire runway so that you didn't even feel the airplane touch down. If you've ever tried to pick something up that has been well greased, then you know what they are referring to. It's very slippery and slides right out of your hands no matter how hard you try.
A "Greaser" is a landing where you lift the nose up a bit high, the rear wheels smoothly hit the runway and the nose gradually comes down. It feels like a very smooth landing but but it uses a lot of runway, so can be a problem on a short runway. Generally it is not considered a good thing! You are also more likely to contact the runway a fair distance past the landing point.