The word 老友 is formed by directly combining two independent concepts: 老 (lǎo), which conveys the idea of something long-established, enduring, or familiar, and 友 (yǒu), which means friend. The formation works through semantic fusion, where 老 modifies and deepens the nature of 友; it doesn't simply mean "old" in an age sense, but imbues the friendship with a sense of time-tested depth, shared history, and enduring closeness. Thus, the compound naturally evokes the complete idea of a "long-time friend" or "old friend", where the history itself is an inseparable quality of the friendship.