ごわい
tegowai

i-Adjective

1. difficult; tough; formidable; redoubtable; stubborn

あいつは海千 うみせん山千 やませんだから、取 相手 あいてとしてはかなり手強 てごわいぞ。
aitsuwa umisen'yamasendakara torihikiaiteto shitewa kanari tegowaizo.
All those tricks he's got up his sleeve make him a formidable client.
Other forms: