A synteny block is a collection of contiguous genes located on the same chromosome. Traits provided by these genes are usually inherited together, thus violating Mendel's law of independent assortment.
Synteny blocks have mostly been preserved by genome rearrangements, and so synteny blocks from two related species (e.g., humans and mice) will be roughly similar but flipped and around on the respective genomes, so that genomic comparison can be achieved by analyzing rearrangements that could have produced the two genomes.
