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