IPA: /ˌpɒlɪˈkloʊnəl/
KK: /pɑlɪˈkloʊnəl/
Relating to or derived from multiple groups of cells that are genetically different from each other.
The researchers used polyclonal antibodies to enhance the immune response in their experiments.
Polyclonal is formed from "poly-" (meaning many) and "clon" (from Greek "klon", meaning twig or branch). The word describes a group of cells or antibodies that originate from multiple clones, hence indicating diversity.
Think of 'many' ('poly-') branches or 'twigs' ('clon') coming from different sources, which helps you remember that 'polyclonal' refers to a variety of origins.
No commonly confused words.