So much confusion and controversy surround the semi landing stance. In a nutshell, the semi is approximately 90 degrees past the mega, or 180 degrees past the hyper, and lands on the inside leg, facing into the momentum of the flip, like mega does. This landing stance allows the performer to swingthrough directly into raiz axis tricks.
The term ‘semi’ itself means half, and is meant to imply being almost to the next rotation up. Because of this, semi landings are hyphenated with the next rotation up, meaning a cork that rotates past mega, but does not yet reach the complete stance for a double rotation is called a semi-double cork. This also allows us to label the landing stances for twists less than 1 complete twist. For example, a gainer that twists approximately 180 degrees, lands on the inside leg, but does not twist past the complete stance (cork) is called a semi-cork. Increasingly, the semi tag is being used at the end of a trick to note a hyper rotation, such as “cork-semi”, or a cork that is over-rotated to the semi position. While this may not be the originally intended use of the semi tag, it is somewhat common, and should be noted.
Another example is a sideswipe with added twist, that does not twist far enough to become a snapu, and lands in the semi position. This would be known as a semi-snapu because snapu, or “snapuswipe”, is the next twist up the chain. In the gif above, the same concept is being applied to a hyperhook. The term for a hyperhook + twist is a kyro, so cutting that twist short, and landing in semi is a semi-btwist-kyro, or btwist-semi-kyro, depending on how you use the terminology.
There is still a lot of confusion for this in the community, so it is important to educate others as often as possible on this matter, and to be accepting of different uses of terminology.