a covenant or compact made between persons, parties, states, etc., for the promotion or maintenance of common interests or for mutual assistance or service.

the aggregation of persons, parties, states, etc., associated in such a covenant or compact; confederacy.

an association of individuals having a common goal.

a group of athletic teams organized to promote mutual interests and to compete chiefly among themselves

a bowling league.

Sports .

major league.

minor league.

group; class; category

As a pianist he just simply isn't in your league.

to unite in a league; combine. ?

in league, working together

often secretly or for a harmful purpose; united.

verb

disassociate

noun

alliance , band , bunch , circle , circuit , club , coalition , combination , combine , compact , company , confederacy , confederation , conference , consortium , crew , gang , group , guild , loop , mob , order , organization , outfit , partnership , pool , ring , society , sodality , union , unit , category , class , grade , grouping , level , pigeonhole * , rank , status , tier , anschluss , bloc , cartel , federation , association , congress , fellowship , fraternity , sorority , bracket , amalgamation , entente

verb

ally , amalgamate , band , coadjute , collaborate , combine , concur , confederate , conjoin , consolidate , cooperate , federate , join forces , unite , align , gang up , alliance , association , brotherhood , circuit , class , coalition , confederacy , conference , division , federation , fellowship , guild , network , order , sisterhood , union