Three-drops water radical, side-form of
水. The indexing radical:
涵 originally described water flowing through a culvert - held, contained, channelled. The water-as-container metaphor blossomed into
包涵 'to encompass / forgive' and
内涵 'inner content.' Same water-containment family:
浸 to soak,
涌 to gush,
流 to flow.