Terms Starting with I

When nothing is forced, improve the least active piece instead of making a move for its own sake

A move that intentionally blocks the coordination, defense, or lines of movement of opponent's pieces. Gaining a tactical advantage by interposing your piece to disrupt the connection between two enemy pieces

A defensive technique of placing a piece between an attacker and the attacked piece (especially the king) to block the attack. Commonly used to block checks by interposing a piece between the checking piece and the king

A pawn with no friendly pawns on adjacent files, making it isolated. It tends to become a weakness as it cannot be supported by other pawns. When it's a d-pawn, it's called an Isolated Queen's Pawn (IQP)