What is the meaning of ABEC ?

ABEC is an acronym for Annular Bearing Engineering Committe of the AFBMA (Anti Fricton Bearing Manufacturers Inc ). The ABEC grades of bearings is a set of standards for the manufacturing tolerances of bearings . All quality manufacturers around the world manufacture to at least ABEC 1 standard. If you were to ask your local bearing supplier for a 608-ZZ  , you would almost certainly receive an ABEC 1 bearing .

Is there a lower grade than ABEC 1 ?

There is no grade lower than ABEC 1 ,but that doesn't mean that a manufacturer  has to meet ABEC standards. There are a lot of small bearing manufacturers that are not publishing  any data on their manufacturing standards, so beware. Be aware that the skate manufacturers are not Bearing Manufacturers. Some well known skate manufactuers may be buying their bearings from the cheapest , least quality conscious bearing manufacturer. Stick to bearing brands that are well known anf you won't go wrong.

Are there any other standards for measuring Bearing precision ?

Yes. The commonly used standard is the ISO ( International Standards Organisation ) standard. There are slight differrences in standards applied, but basically ISO Grade P0 is approximately equal to ABEC 1 ,ISO P6 approximates ABEC 3 , ISO P4 approximates ABEC 7 and ISO P2 approximates ABEC 9.