堅木 is read as かたぎ (katagi) and means hardwood.
かたぎ
katagi
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
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)