From The Collaborative International Dictionary of English v.0.48 [gcide]:
Lastly \Last"ly\, adv.
1. In the last place; in conclusion.
[1913 Webster]
2. at last; finally.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
lastly
adv 1: the item at the end; "last, I'll discuss family values"
[syn: last, lastly, in conclusion, finally]