亘る[wataru] to cross over
幾年にも亘る[ikunennimowataru] extending over a number of years
亘古[kouko] for ever
連亘[renkou] extending in a row

に亘って[niwatatte] throughout
長きに亘る[nagakiniwataru] long (used with period of time)
に亘り[niwatari] throughout

亙る[wataru] to cross over
幾年にも亙る[ikunennimowataru] extending over a number of years

聯亙[renkou] extending in a row
亙古[kouko] from long ago up until the present day

関聯[kanren] relation
聯繋[renkei] connection
聯合[rengou] union
聯想[rensou] association (of ideas)
聯隊[rentai] regiment

聯邦[renpou] commonwealth
聯盟[renmei] league
聯絡[renraku] to contact
聯立[renritsu] alliance
聯句[renku] linked verse

蘇連[soren] (former) Soviet Union
ドイツ連邦共和国[doitsurenpoukyouwakoku] Federal Republic of Germany (former West Germany)
破天連[pateren] Portuguese Jesuits (in Japan in the 16th century)
一連[ichiren] series
引連れる[hikitsureru] to take along with

英連邦[eirenpou] Commonwealth of Nations (formerly British Commonwealth)
欧州連合[oushuurengou] European Union
家族連れ[kazokuzure] taking the family along
関連[kanren] relation
関連会社[kanrengaisha] associated company