m2e :- i know its maven 2 eclipse but 2 stands for maven version 2 or English literal "to" ?
j2ee :- java 2 enterprise edition similarly 2 stands for java version 2 or English literal "to" ?
Both are "version" numbers. J2EE is no longer used, it's Java EE.
I suspect M2E was originally meaning Maven 2, but then evolved to a name.