The Tenkai palm is a card magic technique used to palm a card (to temporarily conceal it during a magic trick). It was invented by the Japanese magician Tenkai, whose real name was Teijiro Ishida (1 December 1889 – 6 June 1972). The Tenkai palm has many applications in card magic such as effects like the snap change and the benzais cop. Additionally, the Tenkai allows much more freedom in the way of palming and revealing.
Tenkai palm Wikipedia
In the Tenkai palm, the card is lengthwise in the hand but is not flat against the palm; the card instead is held between the thumb which lies below and parallel to the palm and the right side of the palm so that the width of the card is clipped by the length of the thumb. While this palm is easily seen from certain angles, it can allow a much more natural appearance for the magician's hand. This palming technique is easily adaptable to coin magic for the use of a jumbo coin (usually 3 inches (7.6 cm) in diameter).