401K Meaning of 401K in English 401K /ˌfɔːr əʊ wʌn ˈkeɪ $ -oʊ-/ BrE AmE in the US, a way of saving money for your ↑ retirement that is handled through the company where you work Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012