Here's why:

* Oligo means "few" or "small" in Greek.

* Nucleotide refers to the building blocks of DNA (and RNA), consisting of a sugar, a phosphate group, and a nitrogenous base.

Therefore, an oligonucleotide is a short chain of nucleotides.

Note: Sometimes the term "primer" is used to describe a short strand of DNA that is used in DNA replication or PCR. This is because primers are designed to be oligonucleotides.