Are "polynucleotide chains" the same as DNA

I think I'm confused. Please help.

A nucleotide is composed of a phosphate, the sugar deoxyribose, and one of the four bases.

DNA is made up of a series of chemical building blocks called nucleotides. Nucleotides join together to form a polynucleotide chain.

So, is a polynucleotide chain the same as a regular DNA strand thing that you see in the twisted ladder formation? OR, is a polynucleotide chain just one half of the DNA strand thing (double helix)?

Basically, yes. You could describe DNA as a polynucleotide chain if you really wanted to, though no one does. And a double helix would technically be two separate chains, with each side being one chain.

Polynucleotide chain could also refer to RNA, because that's also made up of nucleotides.

I'm up to my elbows in DNA every day for my job, and I've never heard the term "polynucleotide chain". Oligonucleotide, sure, but not polynucleotide. Olignucleotides are single stranded. PCR primers, for instance, are oligonucleotides.