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

筝柱[kotoji] bridge of a koto
筝曲[soukyoku] koto music
古筝[kosou] Guzheng (type of ancient Chinese zither)

俗筝[zokusou] modern koto (in contrast to the gagaku koto or gakuso)
楽筝[gakusou] ancient type of koto with 13 strings used in Gagaku music