* Philander: To engage in casual love affairs.
* Philatelist: A collector of stamps.
* Philately: The hobby of collecting stamps.
* Philosopher: A person who studies philosophy.
* Philosophy: The study of fundamental questions about existence, knowledge, values, and reason.
* Philharmonic: Relating to music. (Often used for orchestras)
* Philodendron: A genus of flowering plants.
* Philanthropy: The practice of giving money and time to help make life better for other people.
* Philanthropist: A person who seeks to promote the welfare of others, especially by donating money to good causes.
* Philogynist: A person who loves women.
* Philologist: A scholar of language.
* Philology: The study of language.
* Philomath: A lover of learning.
There are many more words starting with "philo-," but these are some of the most common.