In one's own residence, town, or country. For example, Mary was not at home when I called, or Tourists in a foreign country often behave more rudely than they do at home. This idiom was first recorded in a ninth-century treatise.
Ready to receive a visitor, as in We are always at home to our neighbor's children. This usage gave rise to the noun , meaning a reception to which guests are invited on a specific day at specific hours (also see open house). [c. 1600]
Also, . Comfortable and familiar, as in Mary always makes us feel at home, or I've never been at home with his style of management. [Early 1500s] Also see at ease, def. 1.
Also, at home with. Proficient, well-versed in, as in Young John is so much at home with numbers that he may well become a mathematician, or Chris is really at home in French. [Late 1700s]
In team sports, playing on one's own field or in one's own town. For example, The Red Sox always do better at home than they do at away games.