C.S. Lewis uses the Greek word philia for friendship in The Four Loves.
Published in 1960, The Four Loves examines four terms associated with different kinds of love: affection, friendship, erotic love, and charity. Lewis uses Greek vocabulary to distinguish these forms while also discussing how they overlap in real relationships.
Philia refers to friendship or companionable love. Lewis presents it as a bond based on shared interests, understanding, or a common pursuit. His discussion draws on classical and Christian ideas rather than treating the four categories as rigid psychological types.
The terms are easy to mix up. Storge is associated with affection, eros with sexual or romantic love, and agape with charity or self-giving love. In Lewis’s English title, these categories are discussed as affection, friendship, eros, and charity.