Chemistry is a colloquial synonym for the desire to procreate. It's often used in a bashful or elusive context in bartalk but that's just retarded and lame - just get busy in bed already.
The minority definition has it that chemistry is actually a science. That is, many chemists like to think of it as the study of matter and its interactions, which blatantly bites on the definition of physics. But then again, the materials science definition bites on that of chemistry, so it's really not that bad. One could also define chemistry as the scientific discipline that studies the atomic interactions that are not nuclear.
For the SciForums subforum, see Chemistry (subforum).