user1816: I'm sure most of us have done it at least once ... I had a position where one of my pieces were under direct threat - I was a pawn up, but my opponent attacked my rook with his bishop and threatened to get the pawn back if I was careless. I tried to calculate every possible continuation and got lost in the possibilities ... and before I knew it, I was totally absorbed by the position 4 or 5 moves ahead and completely forgot that my rook was hanging. Keeping a mental eye on the future position instead of the position in front of me, I made a silly move (moved my knight, if I recall) and lost my rook.
Naturally, and quite embarrassingly, my teammates all wanted to know what happened since it looked so good for me at one point. Instead of trying to explain the intricacies of the position, it would be convenient if I could tell my club mates that I lost because of an "X-blunder". Does this type of blunder have a name?

user19877: It does not have a name as far as I have ever read.
That said, what you are describing is not that rare. You are calculating, and the first move is obvious, so you start really calculating at the second move, and when you are done with your calculations, you play the second move, a blunder, first.
I have read about that many times over 40 years, and I have done it myself an an occasion or two.
All you can do is before you execute your move, slow down, and take one last momentary fresh look at the board.

user4425: It's a form of cognitive dissonance. In psychology, cognitive dissonance is the mental stress or discomfort experienced by an individual who holds two or more contradictory beliefs, ideas, or values at the same time, or is confronted by new information that conflicts with existing beliefs, ideas, or values.
The fact that so much of chess is in the mind where pieces are moved about without any actual physical changes on the board, it's easy, especially after a period of time when fatigue becomes a factor, to lose track of what's on the board.
At some point we ALL see things that aren't there and miss things that are.
And that's why playing even a relatively mediocre chess engine is so frustrating. Every move is a fresh position for a Silicon chip or two.

user2429: Alexander Kotov, in his book Think Like a Grandmaster, described this sort of a blunder as a blind spot. 

user4362: It is probably a bit more general than what you describe, but one move blunders are often called (a case of) "chess blindness". 
I'm not a hundred percent sure, what exactly happened in you're case but often people make the second move of a combination (or variation) first, because they are ahead of the actual position. But I don't know a succinct term for that.
If you listen to top players post game interviews, what you hear incredibly often is "I just forgot about move xy". I guess if that description is good enough for Aronian and Co, it is good enough for us. ;-)
Another loosely connected term is "residual image". This describes the case when you are calculating and pieces that already moved, are still on their original square in your mind. 

1816: <p>I'm sure most of us have done it at least once ... I had a position where one of my pieces were under direct threat - I was a pawn up, but my opponent attacked my rook with his bishop and threatened to get the pawn back if I was careless. I tried to calculate every possible continuation and got lost in the possibilities ... and before I knew it, I was totally absorbed by the position 4 or 5 moves ahead and completely forgot that my rook was hanging. Keeping a mental eye on the future position instead of the position in front of me, I made a silly move (moved my knight, if I recall) and lost my rook.</p>

<p>Naturally, and quite embarrassingly, my teammates all wanted to know what happened since it looked so good for me at one point. Instead of trying to explain the intricacies of the position, it would be convenient if I could tell my club mates that I lost because of an "X-blunder". Does this type of blunder have a name?</p>
 19877: <p>It does not have a name as far as I have ever read.</p>

<p>That said, what you are describing is not that rare. You are calculating, and the first move is obvious, so you start really calculating at the second move, and when you are done with your calculations, you play the second move, a blunder, first.</p>

<p>I have read about that many times over 40 years, and I have done it myself an an occasion or two.</p>

<p>All you can do is before you execute your move, slow down, and take one last momentary fresh look at the board.</p>
 4425: <p>It's a form of cognitive dissonance. In psychology, cognitive dissonance is the mental stress or discomfort experienced by an individual who holds two or more contradictory beliefs, ideas, or values at the same time, or is confronted by new information that conflicts with existing beliefs, ideas, or values.</p>

<p>The fact that so much of chess is in the mind where pieces are moved about without any actual physical changes on the board, it's easy, especially after a period of time when fatigue becomes a factor, to lose track of what's on the board.</p>

<p>At some point we ALL see things that aren't there and miss things that are.</p>

<p>And that's why playing even a relatively mediocre chess engine is so frustrating. Every move is a fresh position for a Silicon chip or two.</p>
 2429: <p>Alexander Kotov, in his book Think Like a Grandmaster, described this sort of a blunder as a <a href="http://books.google.com/books?id=CG3RAwAAQBAJ&amp;pg=PA25-IA18&amp;lpg=PA25-IA18&amp;dq=blindspot%20think%20like%20a%20grandmaster&amp;source=bl&amp;ots=qdBD7gUUFU&amp;sig=7GVgWjChSkRXhmI6QvkqPrGgPTE&amp;hl=en&amp;sa=X&amp;ei=VjqHVOyvJtOiugTMyILAAw&amp;ved=0CC8Q6AEwAg#v=onepage&amp;q=blindspot%20think%20like%20a%20grandmaster&amp;f=false" rel="nofollow">blind spot</a>. </p>
 4362: <p>It is probably a bit more general than what you describe, but one move blunders are often called (a case of) "chess blindness". </p>

<p>I'm not a hundred percent sure, what exactly happened in you're case but often people make the second move of a combination (or variation) first, because they are ahead of the actual position. But I don't know a succinct term for that.</p>

<p>If you listen to top players post game interviews, what you hear incredibly often is "I just forgot about move xy". I guess if that description is good enough for Aronian and Co, it is good enough for us. ;-)</p>

<p>Another loosely connected term is "residual image". This describes the case when you are calculating and pieces that already moved, are still on their original square in your mind. </p>
