in which a person will take a special interest in one specific occupation / thing and will pursue that. There are many sub-categories to this word. Such as, a doctor would be a general occupations be he might specialize in gastroenterology. Also used in History / Social Studies class as the term used when (wo)man created civilizations and each person would have a single job, and would barter with other people for necessities.
Bob: Oh, i heard that you're studying to be a scientist Joe.
Joe: Yeah, my specialization is gonna be paleontology