What does the root word epo mean?

The root word "epo" is not a standalone root word in English. It's likely you're thinking of a different word or term.

Could you be referring to one of these?

* "Epi" - This is a common root word meaning "upon," "over," or "on top of." Examples include "epidermis" (skin on top of the body) and "epilogue" (a concluding section at the end of a story).

* "Epo" as part of a specific term like "EPO" which stands for "erythropoietin", a hormone that stimulates red blood cell production.

* "Epo" as a misspelling of a different word?

Please provide more context or the full word/term you're interested in so I can give you a more accurate answer.