What constitutes a unit?

[Ryan Beasley]

Hey guys, I'm relatively new here so bare with me. I was on loopnet browsing through multifamily apartment deals and I came across something confusing. I saw a couple of individual houses that had 2,3 and 4 BEDROOMS and the description on the property said that they contained 2,3, and 4 UNITS. Making them Duplexes, Triplexes and Quadplexes. Have I miss understood what a duplex, triplex and quadplex is? I figured, for example, that a duplex would be two houses combined, both consisting of however many bedrooms (2,3 or more). Am I wrong? Or is a bedroom considered a unit?