Does troops defeated mean the troops I've beaten or my troops that have lost?

Depends on what you are looking at. In the first Page of the Battle Report it says No. of Defeat under your name, thats the amount of troop you defeated.

Death, Slightly wounded, severely wounded and survived are your troops in that part. ,

Under the opponents name it means the Number of troops he defeated from your troops and how many dead/wounded/survived troops he has.

Now if you go into Battle Info its different: you can klick on your or the oppenents name. If you klick on your opponent you see what he lost/wounded/survived, if you klick on your name you see the troops you lost/wounded/survived