A nymph is typically any member of a large class of female mythological entities in human form. They were typically associated with a particular location or landform, such as water, forests, land, etc.
Types of nymphs
- Dryads or eerie wives (forest nymphs)
- Hamadryads (dryads connected with trees)
- Leimoniads (meadow nymphs) 
- Naiads or Rusalkas (river nymphs; it is actually quite possible that they are one and the same)
- Nereids (sea nymphs)
- Oreads (mountain nymphs) 
Creatures similar to nymphs
- Vilas (inhabit hills and forests)
In The Witcher computer game
- Nymphs are creatures of ancient Greek mythology, minor divinities associated with nature, frequently 'targeted' by Satyrs. They have various associations with the great deities of the pantheon, such as Poseidon, Artemis, Apollo and Demeter.