铪（拼音：hā，注音：ㄏㄚ，音同「哈」），是一种化学元素，它的化学符号是Hf，它的原子序数是72，原子量178.49，属周期系ⅣB族。它是一种带光泽的银灰色的过渡金属，熔点2233℃，沸点4602℃，密度13.31克/厘米3。致密的金属铪性质不活泼，表面形成氧化物覆盖层，在常温下很稳定，粉末状的铪容易在空气中自燃。铪吸收氢气的能力很强，最高可形成HfH2.1。高温下，铪能与氮发生反应。由于受镧系收缩的影响，铪的原子半径几乎和锆相等，因此铪与锆的性质极为相似，很难分离，最主要分别是铪的密度是锆的双倍。铪不与稀盐酸、稀硫酸和强碱溶液作用，但可溶于氢氟酸和王水。铪的氧化态是＋2、＋3、＋4，其中＋4价化合物最稳定。

Hafnium is a chemical element with symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, making it the penultimate stable element to be discovered (rhenium was identified two years later). Hafnium is named after Hafnia, the Latin name for Copenhagen, where it was discovered.