Accuracy in LOTRO is called Hit Chance. It determines the chances you have to hit an opponent and not miss. Keep in mind that it doesn't reduce the chance of your attacks to get blocked,parried or evaded.
Your Hit Chance increases by adding points to Agility. Also your Hit Chance reduces when you attack enemies with a higher level than yours and increases when you attack enemies with a lower level. In addition, some weapons reduce your miss chance like swords. For more info please see Hit Chance.