what does it mean to have an engine deburred? saw this mentioned in another post.

 

Remove sharp edges, etc.

 

As above really, remove casting flash, chamfer the main bearing caps and dress those hard nasty corners in the engine casing. Also radius the ring gaps and smooth off piston skirts. Blend ports in the heads etc. It can mean quite a lot of stuff but this depends on who is doing it for you. I do it for stress relief but depending on what part is being worked on can mean it's being done for other reasons such as air flow or reduced friction.