In its broadest sense, theosophy could be described as "any religiophilosophical system purporting to furnish knowledge of God, and of the universe in relation to God, by means of direct mystical intuition, philosophical inquiry, or both." ("Theosophy", in Encarta Encyclopedia)
As such parts of Hinduism, and in particular several ideas of the Upanishads, the I Ching and the Tao Teh Ching, Neo-Platonism, Gnosticism, some Arab philosophies, as well as the cabala all contain theosophical elements.

More specifically, however, the term is most often used for the Theosophical Society that was founded by Madame Blavatsky.

Some core ideas or central themes are: