Hardcast
Hardcast (or Paying Retail) is Magic: The Gathering jargon used to describe the playing of a spell by paying its mana cost instead of using an alternative cost or other ability.
Description
When a spell has an alternative cost, a permanent could be put into play by a means other than casting it, or a card has an ability that can be activated from a zone other than the battlefield, but a player chooses to play the card by paying its mana cost, the player will sometimes state that they are hardcasting it. This is generally done in order to make the play clear to their opponent, particularly when the alternative cost or play is the more common usage of the card.
Examples
Playing Force of Will by paying 
instead of paying 1 life and exiling (pitching) a blue card.
Casting a creature instead of using Aether Vial to put the creature into play.
Casting Simian Spirit Guide instead of exiling it to add 
to your mana pool.
Casting a Decree of Justice or Street Wraith instead of using its cycling ability.
Notes
The inability of some decks to hardcast a portion of their spells (Reanimator, Tooth and Nail, Hypergenesis, or decks based on Sneak Attack) may be an exploitable weakness, as the creatures they want to put into play are dead cards without the respective enablers.