The word "sham" has multiple meanings and can be used in different contexts.
1) In a general sense, it means something that is not genuine or real; an imitation or fake version of something. For example, "That's just a sham friendship - they only hang out when it benefits them."
2) It can also refer to a type of woolen fabric with a napped surface, often used for making clothing items such as jackets and coats. In this context, the word is used more in terms of quality or material rather than authenticity. For example, "I bought this shammy cloth to clean my car."
3) Finally, it can be used as a term of address for someone who is pretending to be something they are not. This usage is typically ironic and playful. For instance, "Hey there, you look like such a sham rockstar with that outfit on!"