γλειφτρόνι = an arse-licker
I have opted for the more vulgar translation because the suffix -ρόνι adds more venom to the original word γλείφτης. Indeed, www.slang.gr describes the suffix as a “γαμοσλανγκοκατάληξη”. I’ll let you work out that one for yourselves! I think the ν in the middle of the word is wrong.
From γλείφω meaning to lick. Βeing called a γλείφτης is not nice, but the prefix κωλο- [as in κωλογλείφτης] raises or lowers it – depending on your viewpoint – to the same level as γλειφτρόνι. You can avoid vulgarity by using κόλακας, but care is needed with συκοφάντης and συκοφαντία as they do not mean sycophant and sycophancy; they mean slanderer and slander.