iron, the metal and the metallic chemical element / (more generally) steel / short for 鉄砲 (teppō, literally “cannon”, but in this case, refers to the poisonous fugu blowfish or dishes made from it)

a wheel furrow, track, or rut / another person's mistake, a prior example (generally negative)

arrowhead / Used instead of 鉄(てつ) (tetsu) in a company logo to avoid to imply 金(かね)を失(うしな)う (kane o ushinau, “lose money”).

Kyūjitai form of 鉄 (“iron”)

spelling

the London Underground

Kyūjitai form of 私鉄 (“private railway”)

(idiomatic) absurd, unbelievable / (idiomatic) extraordinary, enormous

philosophical principles

a male given name