1) Armed forces careerist 2) Army careerist 3) Big house denizen 4) Big house occupant 5) Career employee 6) Career military person 7) Career officer 8) Career soldier 9) Certain con 10) Certain inmate 11) Certain prisoner 12) Comitted one 13) Committed careerist 14) Committed type 15) Constant inmate 1) Con 
A bird species you have never seen before in your life. A lifer allows a birdwatcher to add a tick to their life list.
A first-ever sighting of a bird species by an observer; an addition to one’s life list.
The very first sighting of a bird species that had never been seen before by the observer. 
Lifer is slang for a prisoner condemned to life imprisonment.
career servicemember, as opposed to one who serves for a single enlistment.
[n] - a prisoner serving a term of life imprisonment
slang for a member of the armed services who has volunteered for long service.
noun a prisoner serving a term of life imprisonment
A bird seen for the first time by a birder and added to their life list.