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

御古[ofuru] used article (esp. clothes)
手古摺る[tekozuru] to have much trouble
土耳古[toruko] Turkey
下稽古[shitageiko] rehearsal
懐古[kaiko] recalling the old days

擬古[giko] imitation of classical styles
擬古文[gikobun] classical style
稽古[keiko] practice
遠古登点[wokototen] marks to aid in reading Chinese classics
古え[inishie] antiquity