甲斐[kai] effect
甲斐甲斐しい[kaigaishii] gallant
甲斐性[kaishou] resourcefulness
甲斐無し[kainashi] worthless
生甲斐[ikigai] something one lives for

年甲斐もない[toshigaimonai] unbecoming
友達甲斐[tomodachigai] true friendship
有斐閣[yuuhikaku] Yuuhikaku (law book publisher)
不甲斐ない[fugainai] disappointing
遣り甲斐[yarigai] being worth doing

お遣い[otsukai] errand
遣り繰り[yarikuri] making do
遣り取り[yaritori] giving and taking
遣り方[yarikata] manner of doing
遣る[yaru] to send

遣す[yokosu] to send
為て遣る[shiteyaru] to do for (someone)
かな遣い[kanazukai] kana orthography
気遣い[kizukai] consideration
気遣う[kizukau] to worry about