Verb
(transitive) To increase or complete by adding one or more pieces.
She pieced out a meal for three from what was in the cupboard.
(transitive) To lay out or present possible components of a whole.
He pieced out what he knew from the witnesses.
If any man do not, the quartermaster shall knock the piece out of his hand. Source: Internet
In a situational pin, moving the pinned piece out of the line of attack will result in a situation detrimental to the player of the pinned piece, such as a checkmate. Source: Internet
In this case it is illegal to move the pinned piece out of the line of attack, as that would place one's king in check. Source: Internet