The chemical element iron (Fe); the metal iron itself.
このフライパンは鉄でできている。
This frying pan is made of iron.
鉄は元素記号Feで表され、重要な金属の一つだ。
Iron is represented by the chemical symbol Fe and is one of the important metals.
鉄分が不足すると貧血になりやすい。
A lack of iron can lead to anemia.
Steel (in contexts where 'tetsu' is used to refer to steel/iron used in construction or manufacturing).
橋の骨組みは主に鉄（鋼）で作られている。
The bridge's framework is mainly made of steel.
高温で鍛えられた鉄は強度の高い鋼になる。
Iron forged at high temperatures becomes strong steel.
Used figuratively to mean 'iron' as in strong will, strict discipline, or the epithet 'Iron' (e.g., Iron Lady).
彼女は鉄の意志を持って困難を乗り越えた。
She overcame difficulties with an iron will.
『鉄の女』と呼ばれる政治家がいる。
There is a politician referred to as the 'Iron Lady.'
Abbreviation for 'railway' (used as a prefix/suffix in words like 私鉄, 国鉄).
私鉄・国鉄・市鉄など、『鉄』は『鉄道』の略で使われることが多い。
'Tetsu' is often used as an abbreviation for 'tetsudou' (railway) in terms like wisden private railway (私鉄) or national railway (国鉄).
彼は撮り鉄として週末に沿線へ出かける。
He goes out along the railway lines on weekends as a train-photography enthusiast ('toritetsu').
Colloquial term for a railway enthusiast (used in compounds like 撮り鉄, 乗り鉄).
撮り鉄、乗り鉄、模型鉄など、趣味によって呼び方が分かれる。
There are different kinds of railway enthusiasts—'toritetsu' (photography), 'noritetu' (riding), 'model tetsu', etc.
彼は鉄で、珍しい車両情報に詳しい。
He's a railway enthusiast and knows a lot about rare rolling stock.