The i4Life project has very kindly liberated Catalogue of Life (CoL) data from its database, and you can now download the latest CoL as a set of plain text, tab-separated tables here.
One of the first things I did with my download was check the 'taxa.txt' table for species name popularity*. Here they are, the top 10 species names for animals and plants, with their frequencies in the CoL list and their usual meanings:
Animals
2732 gracilis = slender
2373 elegans = elegant
2231 bicolor = two-coloured
2066 similis = similar
1995 affinis = near
1937 australis = southern
1740 minor = lesser
1718 orientalis = eastern
1708 simplex = simple
1350 unicolor = one-coloured
Plants
1871 gracilis = slender
1545 angustifolia = narrow-leaved
1475 pubescens = hairy
1336 parviflora = few-flowered
1330 elegans = elegant
1324 grandiflora = large-flowered
1277 latifolia = broad-leaved
1155 montana = (of a) mountain
1124 longifolia = long-leaved
1102 acuminata = pointed
Take the numbers cum grano salis. The first thing I did with the CoL tables was check for duplicates, and they're there, unfortunately. It's interesting, though, that gracilis tops the taxonomists' poll for both the animal and plant kingdoms.
*With the GNU/Linux commands
awk -F"\t" '($11 == "Animalia") && ($8 == "species") {print $20}' taxa.txt | sort | uniq -c | sort -nr | head
awk -F"\t" '($11 == "Plantae") && ($8 == "species") {print $20}' taxa.txt | sort | uniq -c | sort -nr | head