永久歯[eikyuushi] permanent tooth
永久性[eikyuusei] permanency
永久脱毛[eikyuudatsumou] removing hair permanently
久しい[hisashii] long
久しく[hisashiku] for a long time

久し振りに[hisashiburini] after a long time
久し振り[hisashiburi] a long time (since the last time)
久懐[kyuukai] long-cherished hope
久慈目[kujime] spotbelly greenling (Hexagrammos agrammus)
久方[hisakata] sky

幾つも[ikutsumo] many
越幾斯[ekisu] extract (esp. of food, fruit, etc.)
沃度丁幾[youdochinki] tincture of iodine
位相幾何学[isoukikagaku] topology
幾つ[ikutsu] how many?

幾つか[ikutsuka] (a) few
幾ら[ikura] how much?
幾らか[ikuraka] some
幾何[kika] geometry