Sentence:  In the early years of EMS, the term <WSD>lifer</WSD> was an entitlement pinned to anyone who  had worked the road for ten years or longer with no real plans of seeking a replacement trade. It was a term that was generally delivered in a respectful and lighthearted teasing manner by someone who by all definitions could have easily been described as a <WSD>lifer</WSD> himself—with the exception of one drawback. So far, the crews didn't know anyone who had worked in the field for ten years, much less  longer ... 
Meaning of the word marked with <WSD> tags:  A person with a singular career path, especially in the military.