Used car sellers on the site use words like "honest", "reliable", and "clean" to tempt buyers.
Only nine out of 1,000 listings used the phrase "second-hand".
Researchers Andrew Kehoe and Matt Gee, from the university's school of English, trawled more than 68,000 items listed and sold on the auction giant's UK site, downloading the listings over a 70-day period before they were analysed.
Dr Kehoe said: "People often think of eBay as a way of getting rid of household junk and unwanted gifts but it actually contains a wide range of products in 35 different categories.
"Sellers write their own descriptions, so we find a lot of language variation ... The language used in eBay descriptions really does have an impact."