Cycloalkenes can, of course, contain more than one double bond. If there are two bonds then the ene ending of the name is replaced with diene. If there are three bonds then the ene ending of the name is replaced with triene. For more double bonds, the Greek prefix is placed in front of the ene ending to indicate the number of double bonds.

 

An example attached:

 

Cyclopenta-1,3-diene

just to note, it is also correct to name it 1,3-Cyclopentadiene. The location of the olefin can be noted outside of the name itself, unless there are other functional groups present. In which case it is necessary to specify the location of the functional groups.

 

Example: Cyclohex-4-ene-3-ol

 

I can't remember if you drop the "a" in hexa or leave it in that situation, anyone know?

Yes you drop the a.