Simply 'Thumb Holes'.
Online websites such as ebay.com and amazon.com
They hold the shirt sleeve when putting on a coat, sweater or an outer garment.
because its a fashion
The mountain with his onionfields saved the lives of Caveman, his greatgrandfather and Zero.
In the novel and movie "Holes," Stanley Yelnats, Jr., was robbed and left for dead in the West Texas desert. He survived by eating the onions he found growing on top of a huge, thumb-shaped rock, which he called "God's Thumb."
If you are trying to make the thumb hole then you just sew a basic button hole (but larger of course)
The first digit of the hand is called the thumb.
The thumb is called a thumb instead of a finger because it is smaller than a finger. A thumb also has 2 joints and a finger has 3.
Big Thumb
Thumb on the back hole and the first three holes on the front.
E on the recorder is... Your back thumb down and your first three fingers, your pointer, middle, and ring finger on the first three holes. Then your next 2 fingers on the two holes before the space with 2 holes.
You put your left thumb on the left thumb hole, and the next two top holes NOT THE REGISTER KEY OR THE A KEY