Synthetic Summon

A Synthetic Summon (合成召喚 Gōsei Shoukan) is the act of Special Summoning a Synthetic Monster from your Extra Deck using "Synthesis", other card effects which explicitly states that the Summon is a Synthetic Summon or the exact way stated in the Synthetic Monster itself.

How to Synthetic Summon
There are two main ways to Synthetic Summon a Synthetic Monster. The first way is to follow the exact requirement in the Synthetic Monster itself. All Synthetic Monsters have their own unique way to summon them. By fulfilling and completing the requirement, then only the player can Synthetic Summon them to their side of the field.

The alternate way is using "Synthesis", which require the Synthetic Material Monsters listed on the Synthetic Monster on your side of the field. By activating "Synthesis", select the Synthetic Monster from your Extra Deck, send the Synthetic Materials to the Graveyard and Synthetic Summon the monster to your side of the field. By using this way, the exact requirement can be skipped.