A sequence of DNA that is recognized by an endonuclease (a protein that cuts DNA) as a site at which the DNA is to be cut
Definition from: GeneReviews
from the University of Washington and the National Center for Biotechnology Information
A specific nucleotide sequence of DNA at which a particular restriction enzyme cuts the DNA. Some sites occur frequently in DNA (e.g., every several hundred base pairs); others much less frequently (rare-cutter; e.g., every 10,000 base pairs).