What is "double replacement reaction"

alt. A chemical reaction involving a change of chemical bonds, so that two compounds become two different compounds, in the form $AB+CDto\; AC+BD$ n. A chemical reaction involving a change of chemical bonds, so that two compounds become two different compounds, in the form $AB+CDto\; AC+BD$

n. a chemical reaction between two compounds where the positive ion of one compound is exchanged with the positive ion of another compound