What is 比肩 (bǐ jiān) in Chinese metaphysics?

Companion: a stem identical to the Day Master in element and polarity (Jia meets Jia). Represents independence, firm will, siblings and peers.

Original (Chinese): 与日主五行同且阴阳同之天干（如甲见甲），代表自主独立、意志坚定、兄弟朋辈与平级伙伴。