CEDICT
magnet (piece of material that attracts some metals by magnetism) (Classifier: 塊／块 m c; 嚿 c)
Wiktionary
以天然磁铁矿加工製成，或以钢、合金钢经磁化后製成的磁体。具有吸引铁、钴、镍等金属的性质。
重編國語辭典
磁石
維基詞典
Earth is like a big magnet.
The earth is like a big magnet.
Source: Tatoeba