Shuffle (シャッフル Shaffuru) is a term that refers to the act of randomizing the order of cards in a player's deck.
Comprehensive Rules[]
1003 Shuffle
1003.1 If there is an instruction to "shuffle (a deck)", the player in charge of the Deck Zone of the designated deck changes the order of cards in their own Deck Zone at random. Afterwards, both players cannot know the position and order of individual cards inside the Deck Zone.
1003.2 If there is a prompt to shuffle a deck that only has 1 card left in the Deck Zone, the deck is still considered as being shuffled even though the card cannot be physically shuffled.
1003.3 If the order of cards in Deck Zone is changed by any method without the instruction to "shuffle", that action is not considered as "shuffle".