Definition - What does Bract Axil mean?
An axil is defined as where a branch joins the main stem, and in the case of grapevines, the bract axil is where the dormant bud develops on the main axil (lateral bud). The two buds are positioned right next to each other on the primary leaf axil, and each bud is capable of growing a shoot.
WineFrog explains Bract Axil
The bract axil is located on the main stem and contains three distinct growing points known as tertiary, secondary and principle buds. The main (principle) bud is the only one that will grow during bud break, but the dormant bud forms in the bract axil. The dormant bud can also have a leaf structure referred to as a compound bud or eye. They usually remain dormant until the next spring, after the main bud has died; the dormant bud will grow if the main bud is damaged or dies but the fruit in the lateral bud will not produce as high of a yield.