When conjugation is possible from either end of the molecule towards the center it is called cross conjugation.

Also conjugation can start from the center of the molecule and moves towards either end.

In cross conjugated compounds there are three groups generally present two of them are not directly in conjugation with each other while both of them are in conjugation with the third as seen in the following examples.

In the first structure aniline, the lone pair on nitrogen activates the ring considerably, as a result bromination under ordinary conditions leads tribromo aniline. While in the second case that is acetanilide, due to cross conjugation the influence of the lone pair in activating the ring is less, hence bromination leads to only mono substituted acetanilide (p-bromoacetanilide).