This is a basic, semi-official glossary list for the game of Dvorak, although you're encouraged to make up your own jargon for your own games. Over the years, we've found that it's useful to have a consistent shorthand for "remove a card from play, but not from someone's hand", rather than picking a verb like "discard" and not being sure how to apply it once the game gets going. A lot of it's been lifted from Magic the Gathering, which is very good at this kind of thing.
Some additional terms (that apply only to some Dvorak games) are defined in the Additional Rules - Physical Challenge.
An Action is a card which, when played, has a one-off effect and is then placed in the discard pile.
Some Things say "Action: [do something]" - this is simply shorthand for "Instead of playing an Action, the player who controls this card may [do something]." (The Thing card remains in play.) This counts as an Action for all relevant purposes - a card which negated Actions would also negate an "instead-of" effect.
Example: If a Thing said "Action: Draw two cards.", then so long as that card remained in play, the player who controlled it could choose to skip their Action for a turn, and draw two cards instead.
The bits of (possibly virtual) cardboard that you use to play Dvorak. All cards in the game are (usually) either Actions or Things.
control / controller
Each Thing has a controller; when a Thing comes into play, its controller is the Player who played it. For clarity, cards controlled by a Player should be placed in front of them on the table. Control of a Thing may change during the course of a game.
If a Thing is "destroyed", it is moved from in play to the discard pile. A Thing that's still in someone's hand can't be destroyed.
Typically if you're told to "discard" a card, it means to move it from your hand to the discard pile. (Things in play are destroyed, not discarded.) Unless a discard is specifically stated as random, the player discarding may choose which card or cards to discard.
Played Actions, destroyed Things and discarded cards end up in a single discard pile, which is placed face-up in view of all players. Anyone may dig through it at any time.
When players draw cards, they move them from the top of the draw pile to their hand. If the draw pile is empty when someone tries to draw a card, the discard pile should be turned over and shuffled to form a new draw pile.
A face-down pile of cards. Players may only dig through the draw pile if a card specifically permits them to. All cards in the deck usually begin the game in the draw pile before players are dealt their starting hands.
A player's hand of cards. Players may only view each others' hands when cards permit them to.
A card is "in play" if it's on the table, rather than in somebody's hand.
A player other than yourself (or a player not on your team, if playing a team game).
If an Action card says that it's a "Reaction", then it's an action that can be played in response to something happening. It counts as an Action for all purposes, except that it doesn't count towards your one-per-turn limit, and you can play it during an opponent's turn if that's when the trigger happened.
Example: "Reaction: When one of your Things is destroyed, destroy all Things."
target / targeted
When an action refers to a "target something", the player who played that action must choose among the somethings available. The chosen item is then "targeted" by that action.
Example: "Destroy target Thing." means that you should choose a Thing, and destroy it. If another card happened to say "Whenever a Thing you control is targeted by Action, draw a card.", then somebody would get to draw a card.
A Thing is a card which, when played, is placed on the table in front of the player who played it. When a Thing is destroyed, it goes to the discard pile.
you / your
If a card refers to "you" it means "the controller of this card". (eg. "You are immune to poison.", "Your Things may not be destroyed.")