1. A growing together of bones originally separated, as of the two pubic bones or the two halves of the lower jawbone.
2. An articulation in which bones are united by cartilage without a synovial membrane or the fusing or growing together of bones such that an abnormal union is formed.
3. A fusion of two similar organs or parts of a plant or the growing together of similar plant parts or organs.
4. Etymology: from New Latin, which came from Greek, "state of growing together", from symphyesthai, "to grow together"; from syn-, "together" + phyein, "to make grow, to bring forth".