堅果 is read as けんか (kenka) and means nut.
けんか
kenka
かたい
obstinate
けんじつ
steady
かたくるしい
formal
けんご
solid
けんちょう
firm (market)
けんじ
holding on to
けんしゅ
strong defense
かたぎ
person in a respectable occupation
かたじん
square
けんぱくどうい
sophism
かたいしょうばい
sound business
けんしん
confirmation (rite)