Endonuclease

Endonucleases are enzymes that cleave the phosphodiester bond within a polynucleotide chain. Restriction endonucleases (Restriction Enzymes) cleave DNA at specific sites, and are divided into three categories, Type I, Type II, and Type III, according to their mechanism of action. These enzymes are often used in genetic engineering to make recombinant DNA for introduction into bacterial, plant, or animal cells.
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Endonuclease /en·do·nu·cle·ase/ any nuclease specifically catalyzing the hydrolysis of interior bonds of ribonucleotide or deoxyribonucleotide [more]Endonuclease - Community and Resources

Noun
1. a nuclease that cleaves nucleic acids at interior bonds and so produces fragments of various sizes
(hypernym) nuclease
(hyponym) restriction endonuclease, restriction nuclease, restriction enzyme

An enzyme that cleaves a nucleic acid (DNA oor RNA) at specific internal sites in the nucleotide base sequence.

A nuclease which cuts a nucleic acid molecule by cleaving the phosphodiester bonds between two internal residues. Best known examples are restriction endonucleases.