Yes it is.
For example, you would say "There are many deer in the park today", not "There are many deers in the park today". It is both singular ("Look at the deer") and plural ("Wow there are a lot of deer over there").
Deer or uncommonly deers
Deer...
deer
vetoes
addresses
mousse as in the hair product
The noun fingers plual, common, concrete noun; the plural form for finger, a word for a thing.
Water Deer Elk Caribou Moose Red Deer Reindeer Chinese Water Deer Roe Deer Sika Deer Fallow Deer Whitetail Deer Mule Deer
Red deer, Wapiti, Sika deer, whitetail deer, Rusa deer, Sambar deer, Fallow deer,
A herd of deer or perhaps a deer park full of deer.
Doe a deer a female deer, ray a drop of golden sun
The collective nouns are a herd of deer, a bunch of deer, a mob of deer, and a parcel of deer.
The red deer, fallow deer, moose, and roe deer.
whitetail deer
Usually INK SAC. Interesting fact: the plual of octopus can be spelled octopus, octopi, octopods, octopus', octopuses, and octopodi - I guess nobody could agree!