Like the feline creatures they share physical similarities with, the nephilim language does sound much like purring and growling to the unlearned. However, it is possible for non-nephilim to learn to understand and speak it.
The language has differing dialects between clans. Though, with many clans dying out much of more obscure dialects have disappeared and recent decades it has been seen that several of the different tribal dialects have merged into one.
When some nephilim speak the common tongue, their speech tends to be interspersed with feline vocables, like purrs or growls. This appears to be a subconscious thing, much like the sibilant hissing of the slithzerikai in any similar situation.
The nephilim also have their own alphabet and works of literature. In contrast to the spoken language, there is very little variation in the written nephilim language between the clans.
The nephilim tend to use their clan as part of their given name, such as Herrrm Split-Tail or Hrror of the Fang.