"What does ___ mean?" (Answers below are from most formal to least) １．＿＿というのはどういう意味ですか。 ２．＿＿っていうのはどういう意味ですか。 ３．＿＿って何？ Another useful phrase: "How do you say ___ in English?" (If you want a translation rather than an explanation) 英語で＿＿は何に当たりますか。 (The literal translation is "what does ___ correspond to in English". The literal Japanese phrase for 'how do you say___ in English' in Japanese is very unnatural)

I would say.. .... はどういう意味ですか .... wa dōiu imi desu ka But it might be better to wait for an answer of a native.