What is meant by the description antiparallel regarding the two strands that make up the dna double helix?

It means that one strand of DNA is in 5'-3' orientation is complementary to other that is in 3'-5' orientation

Explanation:

Two strands in DNA double helix are in opposite directions alongside each other and that is called antiparallel orientation.

The 5' end of nucleic acid refers to phosphoryl end (phosphate group) while 3' end refers to hydroxyl (OH) group.

The property of anti-parallelism is important for the process of DNA replication.