league (n.1) Look up league at Dictionary.com
"alliance," mid-15c., ligg, from Middle French ligue "confederacy, league" (15c.), from Italian lega, from legare "to tie, to bind," from Latin ligare "to bind" (see ligament). Originally among nations, subsequently extended to political associations (1846) and sports associations (1879). League of Nations first attested 1917 (created 1919).
league (v.) Look up league at Dictionary.com
"to form a league," 1610s, from league (n.1). Related: Leagued; leaguing.
league (n.2) Look up league at Dictionary.com
itinerary unit in medieval England, distance of about three statute miles, late 14c., ultimately from Late Latin leuga (source also of French lieue, Spanish legua, Italian lega), which is said by Roman writers to be from Gaulish. A vague measure (perhaps originally an hour's hike), in England it was a conventional, not a legal measure, and in English it is found more often in poetic than in practical writing.